elf: Always honor the first definition in shared object and archive

elf: Always honor the first definition in shared object and archive

GCC doesn't put builtin function symbol references, which are defined in
the shared C library, in the IR symbol table.  When linker rescans shared
objects and archives for newly added symbol references generated from the
IR inputs, it skips definitions of the builtin functions in shared
objects and archives.

Add first_hash to elf_link_hash_table to track unreferenced definitions
defined first in shared objects and archives.  Always use them to resolve
any references.

bfd/

	PR ld/31482
	PR ld/31489
	* elf-bfd.h (elf_link_hash_table): Add first_hash.
	* elflink.c (elf_link_add_to_first_hash): New function.
	(elf_link_add_object_symbols): Initialize first_hash for an IR
	input.  Always use the first definition in shared object.  Add
	the first unreferenced dynamic definition to first_hash.
	(_bfd_elf_archive_symbol_lookup): Add the first unreferenced
	definition to first_hash..
	(elf_link_add_archive_symbols): Use the symbol definition in
	archive if symbol is defined first in this archive.
	(_bfd_elf_link_hash_table_free): Also free first_hash.

ld/

	PR ld/31482
	PR ld/31489
	* testsuite/ld-plugin/lto.exp: Add PR ld/31482 and PR ld/31489
	tests.
	* testsuite/ld-elf/pr31482a-no-lto.c: New file.
	* testsuite/ld-elf/pr31482b-no-lto.c: Likewise.
	* testsuite/ld-elf/pr31482c-no-lto.c: Likewise.
	* testsuite/ld-elf/pr31482d-no-lto.c: Likewise.
	* testsuite/ld-plugin/pass1.out: Likewise.
	* testsuite/ld-plugin/pr31482a.c: Likewise.
	* testsuite/ld-plugin/pr31482b.c: Likewise.
	* testsuite/ld-plugin/pr31482c.c: Likewise.