tsan: disable instrumentation in runtime callbacks in tests

All runtime callbacks must be non-instrumented with the new tsan runtime
(it's now more picky with respect to recursion into runtime).
Disable instrumentation in Darwin tests as we do in all other tests now.

Differential Revision: https://reviews.llvm.org/D114348

compiler-rt/test/tsan/Darwin/debug_external.cpp

@@ -42,7 +42,8 @@ int main() {
   return 0;
 }
 
-void __tsan_on_report(void *report) {
+__attribute__((disable_sanitizer_instrumentation)) void
+__tsan_on_report(void *report) {
   const char *type;
   void *addr;
   void *start;

compiler-rt/test/tsan/Darwin/external-swift-debugging.cpp

@@ -45,8 +45,8 @@ int main(int argc, char *argv[]) {
   fprintf(stderr, "Done.\n");
 }
 
-extern "C"
-void __tsan_on_report(void *report) {
+extern "C" __attribute__((disable_sanitizer_instrumentation)) void
+__tsan_on_report(void *report) {
   const char *description;
   int count;
   int stack_count, mop_count, loc_count, mutex_count, thread_count,