c: Rename uimaxabs to umaxabs

c: Rename uimaxabs to umaxabs

The following patch implements
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3577.txt
No big deal on the GCC side, for uimaxabs we just won't
recognize it as builtin and I don't see it worth preserving
__builtin_uimaxabs, I doubt anything but gcc testsuite used
that.
But on the glibc side I think it will need to remain exported
for ABI compatibility :(

2025-09-01  Jakub Jelinek  <jakub@redhat.com>

	* builtins.def: Implement C2Y N3577 - Rename s/uimaxabs/umaxabs/.
	(BUILT_IN_UIMAXABS): Rename to ...
	(BUILT_IN_UMAXABS): ... this.  Change second argument to "umaxabs".
	* builtins.cc (fold_builtin_1): Use BUILT_IN_UMAXABS rather than
	BUILT_IN_UIMAXABS.

	* gcc.c-torture/execute/builtins/lib/abs.c (uimaxabs): Rename to ...
	(umaxabs): ... this.
	* gcc.c-torture/execute/builtins/uabs-2.c (uimaxabs): Rename to ...
	(umaxabs): ... this.
	(main_test): Use umaxabs instead of uimaxabs.
	* gcc.c-torture/execute/builtins/uabs-3.c (main_test): Use umaxabs
	instead of uimaxabs.