2013-09-26  Tim Shen  <timshen91@gmail.com>

	* regex_error.h: Remove _S_error_last to follow the stanard.
	* regex_scanner.tcc:
	(_Scanner<_FwdIter>::_M_scan_in_brace): Change error_brace to
	error_badbrace.
	(_Scanner<>::_M_eat_escape_posix): Extended doesn't support
	back-reference.