elf/x86: Issue an error on discarded output .plt section

Issue an error, instead of crash, on discarded output .plt section.

bfd/

	PR ld/28597
	* elf32-i386.c (elf_i386_finish_dynamic_sections): Issue an error
	on discarded output .plt section.
	* elf64-x86-64.c (elf_x86_64_finish_dynamic_sections): Likewise.

ld/

	PR ld/28597
	* testsuite/ld-elf/pr28597.d: New file.
	* testsuite/ld-elf/pr28597.s: Likewise.
	* testsuite/ld-elf/pr28597.t: Likewise.
5 files changed