testcase: Fix AIX testsuite failures

Recent testsuite additions trip over AIX-specific features.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/initlist-const1.C: XFAIL on AIX.

gcc/testsuite/g++.dg/cpp0x/initlist-const1.C

@@ -4,4 +4,4 @@
 
 const auto x = { 1, 2 };
 
-// { dg-final { scan-assembler-not {\.data} } }
+// { dg-final { scan-assembler-not {\.data} { xfail powerpc-ibm-aix* } } }