match.pd: Fix popcount (X) + popcount (Y) simplification [PR112719]

match.pd: Fix popcount (X) + popcount (Y) simplification [PR112719]

Since my PR112566 r14-5557 changes the following testcase ICEs, because
.POPCOUNT (x) + .POPCOUNT (y) has a simplification attempted even when
x and y have incompatible types (different precisions).
Note, with _BitInt it can ICE already starting with r14-5435 and
I think as a latent problem it exists for years, because IFN_POPCOUNT
calls inherently can have different argument types and return type
is always the same.
The following patch fixes it by using widest_int during the analysis
(which is where it was ICEing) and if it is optimizable, casting to
the wider type so that bit_ior has matching argument types.

2023-11-28  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/112719
	* match.pd (popcount (X) + popcount (Y) -> POPCOUNT (X | Y)): Deal
	with argument types with different precisions.