Split out LTO's writing of top level asm nodes in preparation of extending

Split out LTO's writing of top level asm nodes in preparation of extending
what needs to be written out when top level asm-s get enhanced to accept a
limited set of input operands.

gcc/
2011-09-30  Jan Beulich  <jbeulich@suse.com>

	* lto-cgraph.c (output_cgraph): Remove processing of
	'cgraph_asm_nodes', call lto_output_toplevel_asms() instead.
	(input_cgraph_1): Remove loop calling cgraph_add_asm_node(), call
	lto_input_toplevel_asms() instead.
	* lto-section-in.c (lto_section_name): Add "asm" entry.
	* lto-streamer-in.c (lto_input_toplevel_asms): New.
	* lto-streamer-out.c (lto_output_toplevel_asms): New.
	* lto-streamer.h (LTO_minor_version): Bump.
	(enum lto_section_type): Add LTO_section_asm.
	(struct lto_asm_header): New.
	(lto_input_toplevel_asms, lto_output_toplevel_asms): Declare.
	* tree-streamer.h (streamer_write_string_cst): Declare.
	* tree-streamer-out.c (write_string_cst): Rename to
	streamer_write_string_cst and make global. Handle incoming string
	being NULL.
	(streamer_write_tree_header): Adjust call to renamed function.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@179386 138bc75d-0d04-0410-961f-82ee72b054a4