Although they aren't passed to linker, we should get it right.
* testsuite/ld-elf/pr22393-2a.rd: Replace "-z textonly" with
"-z separate-code".
* testsuite/ld-elf/pr22393-2b.rd: Likewise.
* testsuite/ld-x86-64/pr22393-3a.rd: Likewise.
* testsuite/ld-x86-64/pr22393-3b.rd: Likewise.