Latest Commits on Master fails for iOS builds

> Note: Please use Issues only for bug reports. For questions, discussions, feature requests, etc. post to dev group: https://www.facebook.com/groups/rocksdb.dev

### Expected behavior

It builds for iOS successfully

### Actual behavior

```
GEN util/build_version.cc
mkdir -p ios-x86/db/
g++ -faligned-new -DHAVE_ALIGNED_NEW -fno-rtti -W -Wextra -Wall -Wsign-compare -Wshadow -Wunused-parameter -Werror -I. -I./include -std=c++11 -DROCKSDB_PLATFORM_POSIX -DROCKSDB_LIB_IO_POSIX -DOS_MACOSX -DIOS_CROSS_COMPILE -DROCKSDB_LITE -Wshorten-64-to-32 -isystem ./third-party/gtest-1.7.0/fused-src -O2 -fno-omit-frame-pointer -momit-leaf-frame-pointer -DNDEBUG -DNDEBUG -Woverloaded-virtual -Wnon-virtual-dtor -Wno-missing-field-initializers -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator11.3.sdk -arch i686 -arch x86_64 -c db/column_family.cc -o ios-x86/db/column_family.o
mkdir -p ios-arm/db/
xcrun -sdk iphoneos g++ -faligned-new -DHAVE_ALIGNED_NEW -fno-rtti -W -Wextra -Wall -Wsign-compare -Wshadow -Wunused-parameter -Werror -I. -I./include -std=c++11 -DROCKSDB_PLATFORM_POSIX -DROCKSDB_LIB_IO_POSIX -DOS_MACOSX -DIOS_CROSS_COMPILE -DROCKSDB_LITE -Wshorten-64-to-32 -isystem ./third-party/gtest-1.7.0/fused-src -O2 -fno-omit-frame-pointer -momit-leaf-frame-pointer -DNDEBUG -DNDEBUG -Woverloaded-virtual -Wnon-virtual-dtor -Wno-missing-field-initializers -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS11.3.sdk -arch armv6 -arch armv7 -arch armv7s -arch arm64 -c db/column_family.cc -o ios-arm/db/column_family.o
In file included from db/column_family.cc:22:
In file included from ./db/compaction_picker.h:18:
In file included from ./db/compaction.h:11:
./db/version_set.h:726:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete metadata;
^
./db/version_set.h:726:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
In file included from db/column_family.cc:24:
In file included from ./db/db_impl.h:23:
In file included from ./db/compaction_job.h:25:
./db/job_context.h:179:7: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete m;
^
./db/job_context.h:179:7: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
In file included from db/column_family.cc:24:
./db/db_impl.h:773:9: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete m;
^
./db/db_impl.h:773:9: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:64:7: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete cfd_;
^
db/column_family.cc:64:7: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:343:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete td;
^
db/column_family.cc:343:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:534:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete mem_->Unref();
^
db/column_family.cc:534:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:539:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete m;
^
db/column_family.cc:539:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:899:10: error: aligned allocation function of type 'void *(std::size_t, std::align_val_t)' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
return new MemTable(internal_comparator_, ioptions_, mutable_cf_options,
^
db/column_family.cc:899:10: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:899:10: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
return new MemTable(internal_comparator_, ioptions_, mutable_cf_options,
^
db/column_family.cc:899:10: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:906:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete mem_->Unref();
^
db/column_family.cc:906:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1217:18: error: aligned allocation function of type 'void *(std::size_t, std::align_val_t)' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
dummy_cfd_(new ColumnFamilyData(0, "", nullptr, nullptr, nullptr,
^
db/column_family.cc:1217:18: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1217:18: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
dummy_cfd_(new ColumnFamilyData(0, "", nullptr, nullptr, nullptr,
^
db/column_family.cc:1217:18: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1239:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete cfd;
^
db/column_family.cc:1239:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1244:3: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete dummy_cfd_;
^
db/column_family.cc:1244:3: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1292:31: error: aligned allocation function of type 'void *(std::size_t, std::align_val_t)' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
ColumnFamilyData* new_cfd = new ColumnFamilyData(
^
db/column_family.cc:1292:31: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1292:31: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
ColumnFamilyData* new_cfd = new ColumnFamilyData(
^
db/column_family.cc:1292:31: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
db/column_family.cc:1320:5: error: aligned deallocation function of type 'void (void *, std::align_val_t) noexcept' is only available on iOS 11 or newer
[-Waligned-allocation-unavailable]
delete cfd;
^
db/column_family.cc:1320:5: note: if you supply your own aligned allocation functions, use -Wno-aligned-allocation-unavailable to silence this diagnostic
17 errors generated.
make: *** [db/column_family.o] Error 1
```

### Steps to reproduce the behavior

1. Clone from master, latest commit: https://github.com/facebook/rocksdb/commit/17339dc2f39a87a9cf097e056a59560b0795ff6e
2. run `TARGET_OS=IOS make static_lib`

This occurs for Xcode 9, 9.2, 9.3, 9.4 and 10 beta 1

__However__ this commit onto master works without an issue: c60df9d9e7629fe208a9b848293a5599f83d5e77