fix build with older gccs: label attributes are only available with gcc 5+

Author: nunoplopes

Zend/zend_portability.h

@@ -219,18 +219,22 @@ char *alloca();
 
 #if defined(__GNUC__) && ZEND_GCC_VERSION >= 4003
 # define ZEND_ATTRIBUTE_UNUSED __attribute__((unused))
-# define ZEND_ATTRIBUTE_UNUSED_LABEL __attribute__((cold, unused));
-# define ZEND_ATTRIBUTE_COLD_LABEL __attribute__((cold));
-# define ZEND_ATTRIBUTE_HOT_LABEL __attribute__((hot));
 # define ZEND_COLD __attribute__((cold))
 # define ZEND_HOT __attribute__((hot))
 #else
 # define ZEND_ATTRIBUTE_UNUSED
+# define ZEND_COLD
+# define ZEND_HOT
+#endif
+
+#if defined(__GNUC__) && ZEND_GCC_VERSION >= 5000
+# define ZEND_ATTRIBUTE_UNUSED_LABEL __attribute__((cold, unused));
+# define ZEND_ATTRIBUTE_COLD_LABEL __attribute__((cold));
+# define ZEND_ATTRIBUTE_HOT_LABEL __attribute__((hot));
+#else
 # define ZEND_ATTRIBUTE_UNUSED_LABEL
 # define ZEND_ATTRIBUTE_COLD_LABEL
 # define ZEND_ATTRIBUTE_HOT_LABEL
-# define ZEND_COLD
-# define ZEND_HOT
 #endif
 
 #if defined(__GNUC__) && ZEND_GCC_VERSION >= 3004 && defined(__i386__)