tsan-ignores-arc-locks.swift: post process test binary on Darwin (#66308)

This allows the `DYLD_LIBRARY_PATH` override to work as expected and
avoid crashes when running.

Addresses rdar://108188149

Author: edymtt

validation-test/Sanitizers/tsan-ignores-arc-locks.swift

@@ -1,4 +1,5 @@
 // RUN: %target-build-swift -sanitize=thread %s -o %t_binary
+// RUN: %target-codesign %t_binary
 // RUN: %env-TSAN_OPTIONS=halt_on_error=1 %target-run %t_binary
 // REQUIRES: executable_test
 // REQUIRES: stress_test
@@ -7,8 +8,6 @@
 
 // Check that TSan ignores the retain count update locks in the runtime.
 
-// REQUIRES: rdar108188149
-
 import Foundation
 
 public class Dummy {