regex.h (basic_regex<>::assign): Don't lose _M_traits.

regex.h (basic_regex<>::assign): Don't lose _M_traits.

2013-08-29  Tim Shen  <timshen91@gmail.com>

	* include/bits/regex.h (basic_regex<>::assign): Don't lose _M_traits.
	  (regex_iterator<>::regex_iterator): Return nullptr when regex_search
	     failed.
	  (regex_token_iterator<>::_M_end_of_seq): Should be defined true when
	    _M_result is(not isn't) nullptr.
	* include/bits/regex_compiler.h: Store _Compiler::_M_traits by reference
	  instead of by value.
	* include/bits/regex_executor.h (_DFSExecutor<>::_DFSExecutor): Add
	  _M_traits to _DFSExecutor.
	* include/bits/regex_executor.tcc (__get_executor<>): Pass traits to
	  _DFSExecutor too.
	* testsuite/28_regex/algorithms/regex_match/extended/wstring_locale.cc:
	  New.
	* testsuite/28_regex/iterators/regex_token_iterator/wchar_t/
	  wstring_02.cc: New.

From-SVN: r202082