[TSan] Ensure test uses tagged pointer

This is a test-only failure. The test wrongly assumes that this gets us
a tagged pointer:
```
NSObject* num1 = @7;
assert(isTaggedPtr(num1));
```

However, on newer deployment targets that have “const data support” we
get a “normal” pointer to constant object.

Radar-Id: rdar://problem/83217293

compiler-rt/test/tsan/Darwin/objc-synchronize-cycle-tagged.mm

@@ -15,7 +15,7 @@ int main(int argc, char* argv[]) {
 
   @autoreleasepool {
     NSObject* obj = [NSObject new];
-    NSObject* num1 = @7;
+    NSObject* num1 = [NSNumber numberWithInt:7];
     NSObject* num2 = [NSNumber numberWithInt:arg];
 
     assert(!isTaggedPtr(obj));