21674.cc: Add xfail on all targets except darwin.

2008-12-18  Jack Howarth  <howarth@bromo.med.uc.edu>

	* testsuite/21_strings/basic_string/element_access/wchar_t/21674.cc:
	Add xfail on all targets except darwin.
	* libstdc++-v3/testsuite/21_strings/basic_string/element_access/char/
	1674.cc: Same.
	* libstdc++-v3/testsuite/22_locale/ctype/is/char/2.cc: Correct syntax
	for xfailing on all targets except linux.

From-SVN: r142819