fab: Use a macro for the atomic/sync builtins case

fab: Use a macro for the atomic/sync builtins case

This is a small cleanup to make it easier to move this part of fab to
somewhere else. And it makes it easier to understand which builtins are being
used here and also less repeated code.

Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* tree-ssa-ccp.cc (CASE_ATOMIC): New defined.
	(CASE_ATOMIC_CMP0): New define.
	(CASE_ATOMIC_BIT_TEST_AND): New defined.
	(pass_fold_builtins::execute): Use CASE_ATOMIC, CASE_ATOMIC_CMP0,
	and CASE_ATOMIC_BIT_TEST_AND.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>