This was introduced with GCC 4.4. This fixes build warnings compiling with
Clang, which pretends to be GCC 4.3 and does not support the "optimize"
attribute.
/* This attribute indicates that the function should be compiled
with the specified LEVEL, regardless of what has been specified
on the command line */
-#if __GNUC__ > 3
+#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR >= 4)
#define OPTIMIZE(LEVEL) ATTRIBUTE ((optimize(LEVEL)))
#else
#define OPTIMIZE(LEVEL)