[gn] Enable stricter build flags

src/base/platform/mutex.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/platform/mutex.h"
 
 #include <errno.h>
 
 namespace v8 {
 namespace base {
@@ skipping 86 matching lines @@
   EnterCriticalSection(cs);
 }
 
 
 static V8_INLINE void UnlockNativeHandle(PCRITICAL_SECTION cs) {
   LeaveCriticalSection(cs);
 }
 
 
 static V8_INLINE bool TryLockNativeHandle(PCRITICAL_SECTION cs) {
-  return TryEnterCriticalSection(cs);
+  return TryEnterCriticalSection(cs) != FALSE;
 }
 
 #endif  // V8_OS_POSIX
 
 
 Mutex::Mutex() {
   InitializeNativeHandle(&native_handle_);
 #ifdef DEBUG
   level_ = 0;
 #endif
@@ skipping 65 matching lines @@
   }
 #ifdef DEBUG
   DCHECK_LE(0, level_);
   level_++;
 #endif
   return true;
 }
 
 }  // namespace base
 }  // namespace v8