Strange unaddr error and sigfault from DynamoRIO during fuzzing

On Fuzzing Android, there is a strange error:

```
16:50|zhaoqin@zhaoqin01:~/Workspace/Packages/ANDROID/android.src/bionic((e75453d...))
> ANDROID_DATA=/.../ANDROID/android.src/out/debug/target/product/generic_x86/data ANDROID_DNS_MODE=local ANDROID_ROOT=/.../ANDROID/android.src/out/debug/target/product/generic_x86/data ~/Workspace/DrMemory/builds/build_x86_drm_rel.git/bin/drmemory -light -fuzz_target '!DrMFuzzerInput|2|0|1|1000' -- /.../ANDROID/android.src/out/debug/target/product/generic_x86/data/nativetest/bionic-unit-tests/bionic-unit-tests32 --gtest_filter=*regex*
...
[==========] Running 2 tests from 1 test case.
~~32207~~ WARNING: application is missing line number information.
...
~~32207~~
~~32207~~ Error #2: UNADDRESSABLE ACCESS: writing 0x00000000-0x00000004 4 byte(s)
~~32207~~ # 0 libdynamorio.so.6.0!memset_mid [/usr/local/google/home/zhaoqin/Workspace/DrMemory/drmemory.git/dynamorio/core/unix/nudgesig.c:86]
~~32207~~ # 1 libdynamorio.so.6.0!dr_call_on_clean_stack [/usr/local/google/home/zhaoqin/Workspace/DrMemory/drmemory.git/dynamorio/core/unix/signal.c:3044]
~~32207~~ Note: @0:00:00.119 in thread 32207
~~32207~~ Note: instruction: rep stos %eax %edi %ecx -> %es:(%edi) %edi %ecx
~~32207~~ Note: 1 threads were executing fuzz targets.
~~32207~~ Note: The error thread was executing the fuzz target with input value:
~~32207~~ Note:
~~32207~~ Note: e1226262 74
~~32207~~ Note:
!DrMFuzzerInput|2|0|1|1000`
0x4ff22fd8 0x711178c1
0xff8bcb2c 0x73915000
0xff8bccb8 0xf6dc03eb
0xff8bcd88 0xf74b17ed
0xff8bcdbc 0x00000000>
[ FAILED ] regex.smoke (120 ms)
```

It has run a lot of iterations after the first error report, so should not be related to the first error report, could be the timeout kill signal not handled well by DrMemory/DynamoRIO.