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.