compiler-gcc{3,4}.h: Use GCC_VERSION macro

Using GCC_VERSION reduces complexity, is easier to read and is GCC's
recommended mechanism for doing version checks.  (Just don't ask me why
they didn't define it in the first place.) This also makes it easy to
merge compiler-gcc{,3,4}.h should somebody want to.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Joe Perches <joe@perches.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>