This reverts commit de8c4bef3329ce0045b8167cdb96d53b2a1509df.
Unfortunately the fix-forward didn't work. Reverting both and will have
Vitaly re-submit.
This reverts commit 52ebd8d0577e07be9c25b56656d1974a84c40bf7.
Missing declaration for gettid() on the buildbot
(https://lab.llvm.org/buildbot/#/builders/72/builds/1592) and unfortunately
a fix-forward attempt for unistd.h didn't work
(de8c4bef3329ce0045b8167cdb96d53b2a1509df). Reverting for now.
Fixes this test compile error:
```
<path>/compiler-rt/test/tsan/debug_alloc_stack.cpp:54:7: error: no matching function for call to '__tsan_get_alloc_stack'
__tsan_get_alloc_stack(mem, trace, num_frames, &thread_id, &thread_os_id);
^~~~~~~~~~~~~~~~~~~~~~
<path>/compiler-rt/test/tsan/debug_alloc_stack.cpp:17:16: note: candidate function not viable: no known conversion from 'uint64_t **' (aka 'unsigned long long **') to 'uint64_t *' (aka 'unsigned long long *') for 5th argument; remove &
extern "C" int __tsan_get_alloc_stack(void *addr, void **trace, size_t size,
^
<path>/compiler-rt/test/tsan/debug_alloc_stack.cpp:61:46: warning: format specifies type 'unsigned long long' but the argument has type 'uint64_t *' (aka 'unsigned long long *') [-Wformat]
fprintf(stderr, "thread os id = 0x%llx\n", thread_os_id);
~~~~ ^~~~~~~~~~~~
1 warning and 1 error generated.
```
