c-common.c, [...]: Remove all references to obstack functions obsoleted by GC...

c-common.c, [...]: Remove all references to obstack functions obsoleted by GC...

	* c-common.c, c-decl.c, c-lang.c, c-lex.c, c-parse.in, c-pragma.c,
	c-typeck.c, objc/objc-act.c: Remove all references to obstack
	functions obsoleted by GC, such as push_obstacks_nochange,
	end_temporary_allocation, savealloc, saveable_tree_cons, etc.
	and code which existed only to decide whether or not to call
	them.  Remove now-unused NESTED argument from start_function;
	all callers changed.  Do not change behavior based on ggc_p.
	The use of the ixp_obstack in c-iterate.c and the util_obstack
	in objc/objc-act.c remain; these are not obsoleted by garbage
	collection.
	* c-tree.h: Update prototype for start_function.

	* c-parse.y, c-parse.c, objc/objc-parse.c, objc/objc-parse.y: Rebuild.

From-SVN: r31611