Add support for enabling DCHECKs in release mode

src/base/platform/mutex.cc

Index: src/base/platform/mutex.cc
diff --git a/src/base/platform/mutex.cc b/src/base/platform/mutex.cc
index 8b1e305701ffcc86190b7f53063a2ca5207a3a41..c781260f1f0f7706479424adf1f92f4717c16a2f 100644
--- a/src/base/platform/mutex.cc
+++ b/src/base/platform/mutex.cc
@@ -112,7 +112,7 @@ static V8_INLINE bool TryLockNativeHandle(PCRITICAL_SECTION cs) {
 
 Mutex::Mutex() {
   InitializeNativeHandle(&native_handle_);
-#ifdef DEBUG
+#if DCHECK_IS_ON
   level_ = 0;
 #endif
 }
@@ -147,7 +147,7 @@ bool Mutex::TryLock() {
 
 RecursiveMutex::RecursiveMutex() {
   InitializeRecursiveNativeHandle(&native_handle_);
-#ifdef DEBUG
+#if DCHECK_IS_ON
   level_ = 0;
 #endif
 }
@@ -161,7 +161,7 @@ RecursiveMutex::~RecursiveMutex() {
 
 void RecursiveMutex::Lock() {
   LockNativeHandle(&native_handle_);
-#ifdef DEBUG
+#if DCHECK_IS_ON
   DCHECK_LE(0, level_);
   level_++;
 #endif
@@ -169,7 +169,7 @@ void RecursiveMutex::Lock() {
 
 
 void RecursiveMutex::Unlock() {
-#ifdef DEBUG
+#if DCHECK_IS_ON
   DCHECK_LT(0, level_);
   level_--;
 #endif
@@ -181,7 +181,7 @@ bool RecursiveMutex::TryLock() {
   if (!TryLockNativeHandle(&native_handle_)) {
     return false;
   }
-#ifdef DEBUG
+#if DCHECK_IS_ON
   DCHECK_LE(0, level_);
   level_++;
 #endif