invoke.texi (Directory Options): Document -iquote.

invoke.texi (Directory Options): Document -iquote.

	* doc/invoke.texi (Directory Options): Document -iquote.
	* doc/cpp.texi: Likewise.
	* doc/cppopts.texi: Likewise.
	* c-opts.c (c_common_missing_argument): Add -iquote processing.
	(c_common_handle_option): Likewise.
	* c.opt (iquote): Add.
	* gcc.h (DEFAULT_WORD_SWITCH_TAKES_ARG): Add -iquote.
	* c-incpath.c (merge_include_chains): Update comment to use -iquote.

	* c-opts.c (case OPT_I): Deprecate -I- support.
	* doc/invoke.texi: Likewise.
	* doc/cpp.texi: Likewise.
	* doc/cppopts.texi: Likewise.

From-SVN: r81521