Disable detection of on_exit()/TSan on NetBSD

[krytarowski]

Summary

NetBSD does not ship with on_exit() function.

Introduce TSAN_MAYBE_INTERCEPT_ON_EXIT.
It looks like this addition fixes build for Darwin.

Sponsored by <The NetBSD Foundation>

lib/tsan/rtl/tsan_interceptors.cc

   // Memory allocation in __cxa_atexit will race with free during exit,
   // because we do not see synchronization around atexit callback list.
   ThreadIgnoreBegin(thr, pc);
   int res = REAL(__cxa_atexit)(at_exit_wrapper, ctx, dso);
   ThreadIgnoreEnd(thr, pc);
   return res;
 }
 
-#if !SANITIZER_MAC
+#if !SANITIZER_MAC && !SANITIZER_NETBSD
 static void on_exit_wrapper(int status, void *arg) {
   ThreadState *thr = cur_thread();
   uptr pc = 0;
   Acquire(thr, pc, (uptr)arg);
   AtExitCtx *ctx = (AtExitCtx*)arg;
   ((void(*)(int status, void *arg))ctx->f)(status, ctx->arg);
   InternalFree(ctx);
 }
 
 TSAN_INTERCEPTOR(int, on_exit, void(*f)(int, void*), void *arg) {
   if (cur_thread()->in_symbolizer)
     return 0;
   SCOPED_TSAN_INTERCEPTOR(on_exit, f, arg);
   AtExitCtx *ctx = (AtExitCtx*)InternalAlloc(sizeof(AtExitCtx));
   ctx->f = (void(*)())f;
   ctx->arg = arg;
   Release(thr, pc, (uptr)ctx);
   // Memory allocation in __cxa_atexit will race with free during exit,
   // because we do not see synchronization around atexit callback list.
   ThreadIgnoreBegin(thr, pc);
   int res = REAL(on_exit)(on_exit_wrapper, ctx);
   ThreadIgnoreEnd(thr, pc);
   return res;
 }
+#define TSAN_MAYBE_INTERCEPT_ON_EXIT TSAN_INTERCEPT(on_exit)
+#else
+#define TSAN_MAYBE_INTERCEPT_ON_EXIT
 #endif
 
 // Cleanup old bufs.
 static void JmpBufGarbageCollect(ThreadState *thr, uptr sp) {
   for (uptr i = 0; i < thr->jmp_bufs.Size(); i++) {
     JmpBuf *buf = &thr->jmp_bufs[i];
     if (buf->sp <= sp) {
       uptr sz = thr->jmp_bufs.Size();

   TSAN_INTERCEPT(gettimeofday);
   TSAN_INTERCEPT(getaddrinfo);
 
   TSAN_INTERCEPT(fork);
   TSAN_INTERCEPT(vfork);
 #if !SANITIZER_ANDROID
   TSAN_INTERCEPT(dl_iterate_phdr);
 #endif
-  TSAN_INTERCEPT(on_exit);
+  TSAN_MAYBE_INTERCEPT_ON_EXIT;
   TSAN_INTERCEPT(__cxa_atexit);
   TSAN_INTERCEPT(_exit);
 
 #ifdef NEED_TLS_GET_ADDR
   TSAN_INTERCEPT(__tls_get_addr);
 #endif
 
 #if !SANITIZER_MAC && !SANITIZER_ANDROID