1. Discard input .note.gnu.build-id sections.
2. Clear the build ID field before writing.
3. Use bfd_make_section_anyway_with_flags to create the output
.note.gnu.build-id section.
PR ld/28639
* ldelf.c (ldelf_after_open): Discard input .note.gnu.build-id
sections, excluding the first one.
(write_build_id): Clear the build ID field before writing.
(ldelf_setup_build_id): Use bfd_make_section_anyway_with_flags
to create the output .note.gnu.build-id section.
* testsuite/ld-elf/build-id.exp: New file.
* testsuite/ld-elf/pr28639a.rd: Likewise.
* testsuite/ld-elf/pr28639b.rd: Likewise.
* testsuite/ld-elf/pr28639c.rd: Likewise.
* testsuite/ld-elf/pr28639d.rd: Likewise.
