* c-common.h (enum rid): Add RID_FIRST_AT, RID_LAST_AT,
	RID_LAST_PQ.  Move RID_FIRST_PQ down with the other FIRST/LAST
	enumerators.
	(OBJC_IS_AT_KEYWORD, OBJC_IS_PQ_KEYWORD): New macros.

	* c-parse.in (OBJC_STRING): Kill.
	(objc_string): Decompose to [objc_string] '@' STRING.
	(reswords): Take the leading '@' off all the Objective C keywords.
	(objc_rid_sans_at): Kill.
	(init_reswords): Don't initialize it.
	(yylexname): Use OBJC_IS_AT_KEYWORD and OBJC_IS_PQ_KEYWORD.
	(_yylex): Kill reconsider label.  Look ahead one token after
	an '@'; if we get an identifier, check whether it's an
	Objective C @-keyword.  If so, return the keyword.  Otherwise,
	put back the token and return the '@' as a terminal.

	* cpplib.c (lex_macro_node): Remove unnecessary check for
	leading '@' on identifier.  Clarify control flow and commentary.

From-SVN: r43674