[compiler-rt][darwin] check for strcmp to test interceptors instead of pthread_create

[aralisza]

Summary

If pthread_create is not available on a platform, we won't be able to check if interceptors work. Use strcmp instead.

[aralisza]

use strcmp

[aralisza]

remove internal_

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

if (DyldNeedsEnvVariable() && !lib_is_in_env) {
     Report("ERROR: The process is launched without DYLD_INSERT_LIBRARIES, "
            "which is required for the sanitizer to work. We tried to set the "
            "environment variable and re-execute itself, but execv() failed, "
            "possibly because of sandbox restrictions. Make sure to launch the "
            "executable with:\n%s=%s\n", kDyldInsertLibraries, new_env);
     RAW_CHECK("execv failed" && 0);
   }
 
-  // Verify that interceptors really work.  We'll use dlsym to locate
-  // "pthread_create", if interceptors are working, it should really point to
-  // "wrap_pthread_create" within our own dylib.
-  Dl_info info_pthread_create;
-  void *dlopen_addr = dlsym(RTLD_DEFAULT, "pthread_create");
-  RAW_CHECK(dladdr(dlopen_addr, &info_pthread_create));
-  if (internal_strcmp(info.dli_fname, info_pthread_create.dli_fname) != 0) {
+  // Verify that interceptors really work. We'll use dlsym to locate
+  // "strcmp", if interceptors are working, it should really point to
+  // "wrap_strcmp" within our own dylib.
+  Dl_info info_strcmp;
+  void *dlopen_addr = dlsym(RTLD_DEFAULT, "strcmp");
+  RAW_CHECK(dladdr(dlopen_addr, &info_strcmp));
+  if (internal_strcmp(info.dli_fname, info_strcmp.dli_fname) != 0) {
     Report(
         "ERROR: Interceptors are not working. This may be because %s is "
         "loaded too late (e.g. via dlopen). Please launch the executable "
         "with:\n%s=%s\n",
         SanitizerToolName, kDyldInsertLibraries, info.dli_fname);
     RAW_CHECK("interceptors not installed" && 0);
   }