PR ld/12365

	PR ld/12365
bfd/
	* elfcode.h (elf_slurp_symbol_table): Put common plugin IR symbols
	in their own common section.
	* elflink.c (elf_link_add_object_symbols): Likewise.
	* linker.c (generic_link_check_archive_element): Don't lose flags
	if common section is pre-existing.
	(_bfd_generic_link_add_one_symbol): Likewise.
ld/
	* ldfile.c (ldfile_try_open_bfd): Move code creating and switching
	to plugin IR BFD..
	* ldmain.c (add_archive_element): ..and similar code here..
	* plugin.c (plugin_maybe_claim): ..to here.  New function.
	(plugin_call_claim_file): Make static.
	(asymbol_from_plugin_symbol): Set ELF st_shndx for common syms.
	(plugin_multiple_common): New function.
	(plugin_call_all_symbols_read): Hook in plugin_multiple_common.
	* plugin.h (plugin_call_claim_file): Don't declare.
	(plugin_maybe_claim): Declare.