Revert "Fix tsan test for Darwin. NFCI."

This reverts commit r304941. Vitaly Buka writes:
"Actually it depends on return value.
Test is for char* version of function. It will probably fail for int
version."

llvm-svn: 304943

compiler-rt/test/tsan/strerror_r.cc

@@ -10,8 +10,7 @@
 char buffer[1000];
 
 void *Thread(void *p) {
-  (void)strerror_r(TEST_ERROR, buffer, sizeof(buffer));
-  return p;
+  return strerror_r(TEST_ERROR, buffer, sizeof(buffer));
 }
 
 int main() {