Skip C tests if test flags include C++ options

	* testsuite/18_support/bad_exception/23591_thread-1.c: Skip test if
	options are present that aren't valid for C.
	* testsuite/abi/header_cxxabi.c: Likewise.

From-SVN: r238988

libstdc++-v3/ChangeLog

 2016-08-02  Jonathan Wakely  <jwakely@redhat.com>
 
+	* testsuite/18_support/bad_exception/23591_thread-1.c: Skip test if
+	options are present that aren't valid for C.
+	* testsuite/abi/header_cxxabi.c: Likewise.
+
 	* testsuite/tr1/5_numerical_facilities/special_functions/16_hermite/
 	check_value.cc: Do not add special functions to namespace std in TR1
 	test.

libstdc++-v3/testsuite/18_support/bad_exception/23591_thread-1.c

 // { dg-require-sharedlib "" }
+// { dg-skip-if "invalid options for C" { *-*-* } { "-std=c++??" "-std=gnu++??" } }
 // { dg-options "-g -O2 -pthread -ldl -x c -fvtable-verify=none -Wno-pedantic" { target *-*-linux* *-*-gnu* *-*-solaris2.1[2-9]* } }
 
 // Copyright (C) 2005-2016 Free Software Foundation, Inc.

libstdc++-v3/testsuite/abi/header_cxxabi.c

 // { dg-do compile }
+// { dg-skip-if "invalid options for C" { *-*-* } { "-std=c++??" "-std=gnu++??" } }
 // { dg-options "-x c" }
 // Copyright (C) 2006-2016 Free Software Foundation, Inc.
 //