Add .gnu.lto_.lto section.

Add .gnu.lto_.lto section.

2019-07-03  Martin Liska  <mliska@suse.cz>

	* lto-section-in.c (lto_get_section_data): Add "lto" section.
	* lto-section-out.c (lto_destroy_simple_output_block): Never
	compress LTO_section_lto section.
	* lto-streamer-out.c (produce_asm): Do not set major_version
	and minor_version.
	(lto_output_toplevel_asms): Likewise.
	(produce_lto_section): New function.
	(lto_output): Call produce_lto_section.
	(lto_write_mode_table): Do not set major_version and
	minor_version.
	(produce_asm_for_decls): Likewise.
	* lto-streamer.h (enum lto_section_type): Add LTO_section_lto
	type.
	(struct lto_header): Remove.
	(struct lto_section): New struct.
	(struct lto_simple_header): Do not inherit from lto_header.
	(struct lto_file_decl_data): Add lto_section_header field.
2019-07-03  Martin Liska  <mliska@suse.cz>

	* lto-common.c: Read LTO section and verify header.

From-SVN: r272995