use a gcc version check in 4.9 warning workaround

url/url_canon_ip.cc

 // Copyright 2013 The Chromium 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 "url/url_canon_ip.h"
 
 #include <stdlib.h>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 187 matching lines @@
   // First, process all components but the last, while making sure each fits
   // within an 8-bit field.
   for (int i = 0; i < existing_components - 1; i++) {
     if (component_values[i] > kuint8max)
       return CanonHostInfo::BROKEN;
     address[i] = static_cast<unsigned char>(component_values[i]);
   }
 
   // Next, consume the last component to fill in the remaining bytes.
   // Work around a gcc 4.9 bug. crbug.com/392872
-#if defined(__GNUC__)
+#if ((__GNUC__ == 4 && __GNUC_MINOR__ >= 9) || __GNUC__ > 4)
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Warray-bounds"
 #endif
   uint32 last_value = component_values[existing_components - 1];
-#if defined(__GNUC__)
+#if ((__GNUC__ == 4 && __GNUC_MINOR__ >= 9) || __GNUC__ > 4)
 #pragma GCC diagnostic pop
 #endif
   for (int i = 3; i >= existing_components - 1; i--) {
     address[i] = static_cast<unsigned char>(last_value);
     last_value >>= 8;
   }
 
   // If the last component has residual bits, report overflow.
   if (last_value != 0)
     return CanonHostInfo::BROKEN;
@@ skipping 476 matching lines @@
   return DoIPv6AddressToNumber<char, unsigned char>(spec, host, address);
 }
 
 bool IPv6AddressToNumber(const base::char16* spec,
                          const Component& host,
                          unsigned char address[16]) {
   return DoIPv6AddressToNumber<base::char16, base::char16>(spec, host, address);
 }
 
 }  // namespace url