* stringpool.c (set_identifier): New function.
	* tree.h: Prototype it.

	* c-parse.in: Kill D_YES. If compiled for objc, call
	save_and_forget_protocol_qualifiers from init_reswords.
	* objc/objc-act.c (remember_protocol_qualifiers,
	forget_protocol_qualifiers): Don't diddle C_IS_RESERVED_WORD.
	Swap out the non-keyword IDENTIFIER_NODEs for keyword ones, or
	vice versa.
	(save_and_forget_protocol_qualifiers): New function.
	* c-lex.h: Prototype save_and_forget_protocol_qualifiers.

From-SVN: r40170