use a gcc version check in 4.9 warning workaround

url/url_canon_ip.cc

Index: url/url_canon_ip.cc
diff --git a/url/url_canon_ip.cc b/url/url_canon_ip.cc
index ee701652bcdfc7e36d8ed843f8c606dda0f9f87f..45f95de0d474bf16a2a64cb928ba0c8517b0b1a3 100644
--- a/url/url_canon_ip.cc
+++ b/url/url_canon_ip.cc
@@ -205,12 +205,12 @@ CanonHostInfo::Family DoIPv4AddressToNumber(const CHAR* spec,
 
   // 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--) {