i386: Allow GOT32 relocations against ABS symbols

GOT32 relocations are allowed since absolute value + addend is stored in
the GOT slot.

Tested on glibc 2.35 build with GCC 11.2 and -Os.

bfd/

	PR ld/28870
	* elfxx-x86.c (_bfd_elf_x86_valid_reloc_p): Also allow GOT32
	relocations.

ld/

	PR ld/28870
	* testsuite/ld-i386/i386.exp: Run pr28870.
	* testsuite/ld-i386/pr28870.d: New file.
	* testsuite/ld-i386/pr28870.s: Likewise.