libcpp: eliminate LINEMAPS_{,ORDINARY_,MACRO_}CACHE

libcpp: eliminate LINEMAPS_{,ORDINARY_,MACRO_}CACHE

It's simpler to use field access than to go through these inline
functions that look as if they are macros.

No functional change intended.

libcpp/ChangeLog:
	* include/line-map.h (maps_info_ordinary::cache): Rename to...
	(maps_info_ordinary::m_cache): ...this.
	(maps_info_macro::cache): Rename to...
	(maps_info_macro::m_cache): ...this.
	(LINEMAPS_CACHE): Delete.
	(LINEMAPS_ORDINARY_CACHE): Delete.
	(LINEMAPS_MACRO_CACHE): Delete.
	* init.cc (read_original_filename): Update for adding "m_" prefix.
	* line-map.cc (linemap_add): Eliminate LINEMAPS_ORDINARY_CACHE in
	favor of a simple field access.
	(linemap_enter_macro): Likewise for LINEMAPS_MACRO_CACHE.
	(linemap_ordinary_map_lookup): Likewise for
	LINEMAPS_ORDINARY_CACHE, twice.
	(linemap_lookup_macro_index): Likewise for LINEMAPS_MACRO_CACHE.

Signed-off-by: David Malcolm <dmalcolm@redhat.com>