Update GTM and enable -Wundef and strict C++11 flags

src/common/mac/GTMLogger.m

 //
 //  GTMLogger.m
 //
 //  Copyright 2007-2008 Google Inc.
 //
 //  Licensed under the Apache License, Version 2.0 (the "License"); you may not
 //  use this file except in compliance with the License.  You may obtain a copy
 //  of the License at
 //
 //  http://www.apache.org/licenses/LICENSE-2.0
 //
 //  Unless required by applicable law or agreed to in writing, software
 //  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 //  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 //  License for the specific language governing permissions and limitations under
 //  the License.
 //
 
 #import "GTMLogger.h"
-#import "GTMGarbageCollection.h"
 #import <fcntl.h>
 #import <unistd.h>
 #import <stdlib.h>
 #import <pthread.h>
 
 
 #if !defined(__clang__) && (__GNUC__*10+__GNUC_MINOR__ >= 42)
 // Some versions of GCC (4.2 and below AFAIK) aren't great about supporting
 // -Wmissing-format-attribute
 // when the function is anything more complex than foo(NSString *fmt, ...).
@@ skipping 468 matching lines @@
       return NO;
     }
   }
   return [[NSUserDefaults standardUserDefaults] boolForKey:kVerboseLoggingKey];
 }
 // COV_NF_END
 
 // In DEBUG builds, log everything. If we're not in a debug build we'll assume
 // that we're in a Release build.
 - (BOOL)filterAllowsMessage:(NSString *)msg level:(GTMLoggerLevel)level {
-#if DEBUG
+#if defined(DEBUG) && DEBUG
   return YES;
 #endif
 
   BOOL allow = YES;
 
   switch (level) {
     case kGTMLoggerLevelDebug:
       allow = NO;
       break;
     case kGTMLoggerLevelInfo:
@@ skipping 83 matching lines @@
              NSMakeRange(kGTMLoggerLevelUnknown, level + 1)]];
 }
 
 @end  // GTMLogMaximumLevelFilter
 
 #if !defined(__clang__) && (__GNUC__*10+__GNUC_MINOR__ >= 42)
 // See comment at top of file.
 #pragma GCC diagnostic error "-Wmissing-format-attribute"
 #endif  // !__clang__