Enabling work for C++ handling of misspelled identifiers and typenames

Enabling work for C++ handling of misspelled identifiers and typenames

gcc/c/ChangeLog:
	* c-decl.c (struct edit_distance_traits<cpp_hashnode *>): Move to
	spellcheck-tree.h
	(best_macro_match): Likewise, converting from a typedef to a
	subclass.
	(find_closest_macro_cpp_cb): Move to spellcheck-tree.c.
	(lookup_name_fuzzy): Update for change of best_macro_match to a
	subclass with a ctor that calls cpp_forall_identifiers.

gcc/ChangeLog:
	* diagnostic-show-locus.c (diagnostic_show_locus): If this is the
	same location as last time, don't skip if we have fix-it hints.
	Clarify the skipping logic by converting it from one "if" clause
	to repeated "if" clauses.
	* spellcheck-tree.c: Include "cpplib.h".
	(find_closest_macro_cpp_cb): Move here from c/c-decl.c.
	(best_macro_match::best_macro_match): New constructor.
	* spellcheck-tree.h (struct edit_distance_traits<cpp_hashnode *>):
	Move here from c/c-decl.c.
	(class best_macro_match): Move here from c/c-decl.c, converting
	from a typedef to a subclass, gaining a ctor.

From-SVN: r238522