regex_compiler.h (__detail::_BracketMatcher): Reorder members to avoid wasted space when not using a cache.

	* include/bits/regex_compiler.h (__detail::_BracketMatcher): Reorder
	members to avoid wasted space when not using a cache.
	(__detail::_BracketMatcher::_M_ready()): Sort and deduplicate set.
	* include/bits/regex_compiler.tcc
	(__detail::_BracketMatcher::_M_apply(_CharT, false_type)): Use binary
	search on set.
	* include/bits/regex_executor.h (__detail::_Executor::_Match_mode):
	New enumeration type to indicate match mode.
	(__detail::_Executor::_State_info): New type holding members only
	needed in BFS-mode. Replace unique_ptr<vector<bool>> with
	unique_ptr<bool[]>.
	(__detail::_Executor::_M_rep_once_more, __detail::_Executor::_M_dfs):
	Replace template parameter with run-time function parameter.
	(__detail::_Executor::_M_main): Likewise. Dispatch to ...
	(__detail::_Executor::_M_main_dispatch): New overloaded functions to
	implement DFS and BFS mode.
	* include/bits/regex_executor.tcc (__detail::_Executor::_M_main):
	Split implementation into ...
	(__detail::_Executor::_M_main_dispatch): New overloaded functions.
	(__detail::_Executor::_M_lookahead): Create nested executor on stack.
	(__detail::_Executor::_M_rep_once_more): Pass match mode as function
	argument instead of template argument.
	(__detail::_Executor::_M_dfs): Likewise.
	* include/bits/regex_scanner.tcc: Fix typos in comments.
	* testsuite/performance/28_regex/range.cc: New.

From-SVN: r211143