Add C++11 std::string constructors for locales and facets.

Add C++11 std::string constructors for locales and facets.

	* config/abi/pre/gnu.ver: Export new constructors.
	* include/bits/codecvt.h (codecvt_byname): Add string constructor.
	(codecvt_byname<char16_t>, codecvt_byname<char32_t>): Define explicit
	specializations and declare explicit instantiations.
	* include/bits/locale_classes.h (locale, collate_byname): Add string
	constructors.
	* include/bits/locale_facets.h (ctype_byname, numpunct_byname):
	Likewise.
	* include/bits/locale_facets_nonio.h (time_get_byname,
	time_put_byname, moneypunct_byname, messages_byname): Likewise.
	* src/c++11/codecvt.cc (codecvt_byname<char16_t>,
	codecvt_byname<char32_t>): Define explicit instantiations.
	* src/c++11/locale-inst.cc (time_put_byname, codecvt_byname):
	Instantiate string constructors.
	(ctype_byname): Define string constructor.
	* testsuite/22_locale/codecvt_byname/1.cc: New.
	* testsuite/22_locale/collate_byname/1.cc: New.
	* testsuite/22_locale/ctype_byname/2.cc: New.
	* testsuite/22_locale/messages_byname/1.cc: New.
	* testsuite/22_locale/moneypunct_byname/1.cc: New.
	* testsuite/22_locale/numpunct_byname/1.cc: New.

From-SVN: r219887