Import latest fixes to libiberty from GCC.

Import latest fixes to libiberty from GCC.

	PR lto/81968
	* simple-object-elf.c (simple_object_elf_copy_lto_debug_section):
	Keep names of removed global symbols.

	* simple-object-xcoff.c (simple_object_xcoff_find_sections):
	Improve .go_export csect handling.  Don't make assumptions
	on containing section or number of auxiliary entries.

	PR lto/81968
	* simple-object-elf.c (simple_object_elf_copy_lto_debug_section):
	Adjust field with for sh_type write, set SHF_EXCLUDE only for
	removed sections.

	PR lto/81925
	* simple-object-elf.c (simple_object_elf_write_shdr): Adjust
	type of sh_addralign and sh_entsize and properly write
	sh_entsize as Elf_Addr.
	(simple_object_elf_write_to_file): Read sh_entsize as Elf_Addr.

	* simple-object-common.h (struct simple_object_functions): Add
	copy_lto_debug_sections hook.
	* simple-object.c: Include fcntl.h.
	(handle_lto_debug_sections): New helper function.
	(simple_object_copy_lto_debug_sections): New function copying
	early LTO debug sections to regular debug sections in a new file.
	(simple_object_start_write): Handle NULL segment_name.
	* simple-object-coff.c (simple_object_coff_functions): Adjust
	for not implemented copy_lto_debug_sections hook.
	* simple-object-mach-o.c (simple_object_mach_o_functions): Likewise.
	* simple-object-xcoff.c (simple_object_xcoff_functions): Likewise.
	* simple-object-elf.c (SHT_NULL, SHT_SYMTAB, SHT_RELA, SHT_REL,
	SHT_GROUP): Add various sectopn header types.
	(SHF_EXCLUDE): Add flag.
	(Elf32_External_Sym, Elf64_External_Sym): Add symbol struct.
	(ELF_ST_BIND, ELF_ST_TYPE, ELF_ST_INFO): Add accessors.
	(STT_OBJECT, STT_FUNC, STT_TLS, STT_GNU_IFUNC): Add Symbol types.
	(STV_DEFAULT): Add symbol visibility.
	(SHN_COMMON): Add special section index name.
	(struct simple_object_elf_write): New.
	(simple_object_elf_start_write): Adjust for new private data.
	(simple_object_elf_write_shdr): Pass in values for all fields
	we write.
	(simple_object_elf_write_to_file): Adjust.  Copy from recorded
	section headers if requested.
	(simple_object_elf_release_write): Release private data.
	(simple_object_elf_copy_lto_debug_sections): Copy and rename sections
	as denoted by PFN and all their dependences, symbols and relocations
	to the empty destination file.
	(simple_object_elf_functions): Adjust for copy_lto_debug_sections hook.

	* simple-object-xcoff.c (simple_object_xcoff_find_sections):
	Search symbol table for .go_export symbol and apply pfn if found.