[test][sanitizer] Disable create_thread_loop on Darwin

[steven_wu]

Summary

create_thread_loop can time out sometimes on macOS CI.

[steven_wu]

See https://green.lab.llvm.org/green/job/clang-stage1-RA/

[steven_wu]

Committed to fix the bot. Let me know if there is post commit review or other feedbacks.

compiler-rt/test/sanitizer_common/TestCases/Posix/create_thread_loop.cpp

 // Simple stress test for of pthread_create. Increase arg to use as benchmark.
 
 // RUN: %clangxx -O3 -pthread %s -o %t && %run %t 1000
 
-// Inconsistently fails on Android.
-// UNSUPPORTED: android
+// Inconsistently fails on Android and can timeout on darwin platforms.
+// UNSUPPORTED: android, darwin
 
 #include <pthread.h>
 #include <stdlib.h>
 
 extern "C" const char *__asan_default_options() {
   // 32bit asan can allocate just a few FakeStacks.
   return sizeof(void *) < 8 ? "detect_stack_use_after_return=0" : "";
 }