RocksJava Crashes when compiled with jemalloc on MacOS

I guess this is the follow on issue from https://github.com/facebook/rocksdb/issues/2954

After compiling RocksDB (today's git `HEAD` of `master`) on MacOS, if you run `make jtest` then you get a SIGSEGV in a call to `jemalloc`.

* macOS Mojave - 10.14.5
* Apple LLVM version 10.0.1 (clang-1001.0.46.4)
* Oracle JDK 1.7.0_80-b15 64-Bit Server VM
* jemalloc 5.2.1 (installed via homebrew)

The `jtest` suite appears to complete successfully, but then we get the SIGSEGV:

```
Time: 133.129

OK (883 tests)

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00000001201a7f6c, pid=18203, tid=9987
#
# JRE version: Java(TM) SE Runtime Environment (7.0_80-b15) (build 1.7.0_80-b15)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (24.80-b11 mixed mode bsd-amd64 compressed oops)
# Problematic frame:
# C [libjemalloc.2.dylib+0x6f6c] je_free_default+0xab
#
```

The Java error report stack looks like (full stack attached - [hs_err_pid18203.log](https://github.com/facebook/rocksdb/files/3596902/hs_err_pid18203.log)):

```
Stack: [0x000070000d9c5000,0x000070000dac5000], sp=0x000070000dac4c00, free space=1023k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [libjemalloc.2.dylib+0x6f6c] je_free_default+0xab
C [libjemalloc.2.dylib+0x44c5a] zone_free+0xaf
C [CoreFoundation+0x13c9af] _CFRelease+0x2c0
C [SystemConfiguration+0x6a27] __SCThreadSpecificDataFinalize+0x2a
C [libsystem_pthread.dylib+0x3660] _pthread_tsd_cleanup+0x1dc
C [libsystem_pthread.dylib+0x6655] _pthread_exit+0x46
C [libsystem_pthread.dylib+0x32f6] _pthread_body+0x89
C [libsystem_pthread.dylib+0x6249] _pthread_start+0x42
C [libsystem_pthread.dylib+0x240d] thread_start+0xd
```