ASan: build an uninstrumented version of pthread_join

Reading `t->self` will somehow trigger an heap-use-after-free by ASan.

Author: kleisauke

system/lib/libc/musl/src/thread/pthread_detach.c

@@ -4,9 +4,7 @@
 static int __pthread_detach(pthread_t t)
 {
 #ifdef __EMSCRIPTEN__ // XXX Emscripten return ESRCH when attempting to detach invalid threads
-	if (!t || t->self != t) {
-		return ESRCH;
-	}
+	if (!t || t->self != t) return ESRCH;
 #endif
 	/* If the cas fails, detach state is either already-detached
 	 * or exiting/exited, and pthread_join will trap or cleanup. */

system/lib/libc/musl/src/thread/pthread_join.c

@@ -7,12 +7,16 @@ static void dummy1(pthread_t t)
 }
 weak_alias(dummy1, __tl_sync);
 
+// XXX Emscripten ASan: build an uninstrumented version of pthread_join
+#if defined(__EMSCRIPTEN__) && defined(__has_feature)
+#if __has_feature(address_sanitizer)
+__attribute__((no_sanitize("address")))
+#endif
+#endif
 static int __pthread_timedjoin_np(pthread_t t, void **res, const struct timespec *at)
 {
 #ifdef __EMSCRIPTEN__ // XXX Emscripten return ESRCH when attempting to join invalid threads (see test_pthread_join_6_2)
-	if (!t || t->self != t) {
-		return ESRCH;
-	}
+	if (!t || t->self != t) return ESRCH;
 #endif
 
 	int state, cs, r = 0;