[compiler-rt] Fix TLS resource leaking in unittest

[etienneb]

Summary

The thread specific key wasn't not released.
Running the unittest in loop will fail after 1024 iteraions.

./projects/compiler-rt/lib/sanitizer_common/tests/Sanitizer-i386-Test --gtest_filter=SanitizerCommon.PthreadDestructorIterations --gtest_repeat=2000 --gtest_break_on_failure

Repeating all tests (iteration 1023) . . .

Note: Google Test filter = SanitizerCommon.PthreadDestructorIterations
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from SanitizerCommon
[ RUN      ] SanitizerCommon.PthreadDestructorIterations
/usr/local/google/home/etienneb/llvm/llvm/projects/compiler-rt/lib/sanitizer_common/tests/sanitizer_posix_test.cc:54: Failure
Value of: pthread_key_create(&key, &destructor)
  Actual: 11
Expected: 0
Aborted (core dumped)

[etienneb]

nits

[rnk]

lgtm

Feel free to just commit these kinds of one line fixes.

lib/sanitizer_common/tests/sanitizer_posix_test.cc

 }
 
 TEST(SanitizerCommon, PthreadDestructorIterations) {
   ASSERT_EQ(0, pthread_key_create(&key, &destructor));
   SpawnThread(GetPthreadDestructorIterations());
   EXPECT_TRUE(destructor_executed);
   SpawnThread(GetPthreadDestructorIterations() + 1);
   EXPECT_FALSE(destructor_executed);
+  ASSERT_EQ(0, pthread_key_delete(key));
 }
 
 TEST(SanitizerCommon, IsAccessibleMemoryRange) {
   const int page_size = GetPageSize();
   uptr mem = (uptr)mmap(0, 3 * page_size, PROT_READ | PROT_WRITE,
                         MAP_PRIVATE | MAP_ANON, -1, 0);
   // Protect the middle page.
   mprotect((void *)(mem + page_size), page_size, PROT_NONE);