MATCH: add some of what phiopt's builtin_zero_pattern did

This adds the patterns for
POPCOUNT BSWAP FFS PARITY CLZ and CTZ.
For "a != 0 ? FUNC(a) : CST".
CLRSB, CLRSBL, and CLRSBLL will be moved next.

Note this is not enough to remove
cond_removal_in_builtin_zero_pattern as we need to handle
the case where there is an NOP_CONVERT inside the conditional
to move out of the condition inside match_simplify_replacement.

OK? Bootstrapped and tested on x86_64-linux-gnu.

gcc/ChangeLog:

	* match.pd: Add patterns for "a != 0 ? FUNC(a) : CST"
	for FUNC of POPCOUNT BSWAP FFS PARITY CLZ and CTZ.