There is no need to generate x86 ISA properties with empty bits in
linker output.
bfd/
PR ld/23372
* elfxx-x86.c (_bfd_x86_elf_merge_gnu_properties): Remove x86
ISA properties with empty bits.
ld/
PR ld/23372
* testsuite/ld-i386/i386.exp: Run pr23372a and pr23372b.
* testsuite/ld-i386/pr23372a.d: New file.
* testsuite/ld-i386/pr23372a.s: Likewise.
* testsuite/ld-i386/pr23372b.d: Likewise.
* testsuite/ld-i386/pr23372b.s: Likewise.
* testsuite/ld-i386/pr23372c.s: Likewise.
* testsuite/ld-x86-64/pr23372a-x32.d: Likewise.
* testsuite/ld-x86-64/pr23372a.d: Likewise.
* testsuite/ld-x86-64/pr23372a.s: Likewise.
* testsuite/ld-x86-64/pr23372b-x32.d: Likewise.
* testsuite/ld-x86-64/pr23372b.d: Likewise.
* testsuite/ld-x86-64/pr23372b.s: Likewise.
* testsuite/ld-x86-64/pr23372c.s: Likewise.
* testsuite/ld-x86-64/x86-64.exp: Run pr23372a, pr23372a-x32,
pr23372b and pr23372b-x32.
