PR libstdc++/67015
	* include/bits/regex_compiler.h (_Compiler<>::_M_expression_term,
	_BracketMatcher<>::_M_add_collating_element): Change signature
	to make checking the and of bracket expression easier.
	* include/bits/regex_compiler.tcc (_Compiler<>::_M_expression_term):
	Treat '-' as a valid literal if it's at the end of bracket expression.
	* testsuite/28_regex/algorithms/regex_match/cstring_bracket_01.cc:
	New testcases.

From-SVN: r226336