Remove ignored "xfail" from dg-do compile directives

Remove ignored "xfail" from dg-do compile directives

	* testsuite/23_containers/unordered_map/requirements/53339.cc: Remove
	ignored "xfail" from { dg-do compile { xfail selector } } directive.
	* testsuite/23_containers/unordered_multimap/requirements/53339.cc:
	Likewise.
	* testsuite/26_numerics/headers/cmath/
	c99_classification_macros_c++11.cc: Likewise.
	* testsuite/26_numerics/headers/cmath/
	c99_classification_macros_c++98.cc: Likewise.
	* testsuite/26_numerics/headers/cmath/
	c99_classification_macros_c.cc: Likewise.

From-SVN: r238954