Implement bracket expression.

Implement bracket expression.

2013-08-03  Tim Shen  <timshen91@gmail.com>

	Implement bracket expression.
	* include/bits/regex.h: Remove constexpr from "|=", etc.
	* include/bits/regex_compiler.h: Parse bracket expression.
	* include/bits/regex_nfa.h: _Comparator and _BracketMatcher(old
	_RangeMatcher).
	* include/bits/regex_nfa.tcc: Implement them.
	* testsuite/28_regex/algorithms/regex_match/extended/53622.cc:
	from regex_search to regex_match.
	* testsuite/28_regex/algorithms/regex_match/extended/
	cstring_bracket_01.cc: New.

From-SVN: r201465