Add some functions for use by the RTL frontend.

Add some functions for use by the RTL frontend.

gcc/ChangeLog:
	* read-md.c (rtx_reader::require_char): New method.
	(require_char_ws): Convert from function to...
	(rtx_reader::require_char_ws): ...method.
	(rtx_reader::require_word_ws): New method.
	* read-md.h (rtx_reader::require_char): New method decl.
	(require_char_ws): Remove global decl in favor of...
	(rtx_reader::require_char_ws): ...new method decl.
	(rtx_reader::require_word_ws): New method decl.
	(rtx_reader::peek_char): New method decl.

From-SVN: r243376