* config/abi/pre/gnu.ver: Export new symbols.
	* include/Makefile.am: Add codecvt.
	* include/Makefile.in: Regenerate.
	* include/std/codecvt: New header.
	* src/c++11/codecvt.cc (__codecvt_utf8_base, __codecvt_utf16_base,
	__codecvt_utf8_utf16_base): Define specializations.
	* testsuite/22_locale/codecvt/codecvt_utf8/requirements/1.cc: New.
	* testsuite/22_locale/codecvt/codecvt_utf16/requirements/1.cc: New.
	* testsuite/22_locale/codecvt/codecvt_utf8_utf16/requirements/1.cc:
	New.

From-SVN: r219779