* include/bits/regex.h
	(basic_regex::assign(const C*, size_t, flag_type)): Add default
	argument (LWG 3296).
	* testsuite/28_regex/basic_regex/assign/char/lwg3296.cc: New test.
	* testsuite/28_regex/basic_regex/assign/wchar_t/lwg3296.cc: New test.

From-SVN: r276121