build: Use GNU as options on most x86/SPARC systems [PR123841,PR123926]

build: Use GNU as options on most x86/SPARC systems [PR123841,PR123926]

The GNU as --32 and --64 options are now applied to all x86 and SPARC
systems other than Darwin and Solaris with the native assembler.

Tested on {i386,amd64}-pc-solaris2.11, sparc{,v9}-sun-solaris2.11,
{x86_64,i686}-pc-linux-gnu, amd64-pc-freebsd15.0, and
sparc64-unknown-linux-gnu.

2026-01-28  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	gcc:
	PR other/123841
	PR target/123926
	* acinclude.m4 (gcc_GAS_FLAGS): Handle non-Darwin/Solaris as cases
	alike on x86 and SPARC.
	* configure: Regenerate.