This patch assigns explicit integers to enum values corresponding
to the plugin API.  This patch helps preventing problems while
cherry-picking plugin-api.h changes from trunk gold to local branches.
For instance, a linker plugin compiled with a cherry-picked
plugin-api.h header with some enum values missing will behave
strangely when used with a linker built with the up to date header.


	* plugin-api.h (enum ld_plugin_level): Assign integers
	explicitly for all values.
* pathnames.sgml: Clarify '@' processing.
* pathnames.sgml: Remove stray '@'.
	* configure.ac: Sync with GCC repo.
	* configure: Ditto.
include/
	* bfdlink.h (struct bfd_link_info): Delete emit_note_gnu_build_id.
bfd/
	* configure.in: Bump version to 2.23.52.
	* elf-bfd.h (struct elf_build_id_info): New.
	(struct elf_obj_tdata): Delete after_write_object_contents,
	after_write_object_contents_info and build_id_size.  Make build_id
	a pointer to struct elf_build_id_info.
	* elf.c (_bfd_elf_write_object_contents): Style.  Update
	after_write_ibject_contents invocation.
	(elfobj_grok_gnu_build_id): Update for new build_id struct.  Don't
	allow zero size notes.
	* configure: Regenerate.
gdb/
	* elfread.c (struct build_id): Delete.  Use struct elf_build_id
	throughout file instead.
	(build_id_bfd_get): Update to use new elf_tdata build_id field.
	Don't xmalloc return value.
	(build_id_verify): Similarly.  Don't xfree.
	(build_id_to_debug_filename): Update.
	(find_separate_debug_file_by_buildid): Update, don't xfree.
ld/
	* emultempl/elf32.em (emit_note_gnu_build_id): New static var.
	Replace all info->emit_note_gnu_build_id refs.
	(id_note_section_size): Rename from
	gld${EMULATION_NAME}_id_note_section_size.
	(struct build_id_info): Delete.
	(write_build_id): Rename from
	gld${EMULATION_NAME}_write_build_id_section.
	Update elf_tdata usage.  Style, formatting.
	(setup_build_id): New function.
	(gld${EMULATION_NAME}_after_open): Use setup_build_id.
	* libc/machine/mips/memcpy.S: Fix USE_PREFETCH check.
Merge branch 'cygwin' into msys2-1.0-dev