Put CPPBackend tests into their own directory and run them only if they're
supported.

llvm-svn: 53427
diff --git a/llvm/test/CodeGen/CPP/dg.exp b/llvm/test/CodeGen/CPP/dg.exp
new file mode 100644
index 0000000..3276dcc
--- /dev/null
+++ b/llvm/test/CodeGen/CPP/dg.exp
@@ -0,0 +1,5 @@
+load_lib llvm.exp
+
+if { [llvm_supports_target CppBackend] } {
+  RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.{ll,c,cpp}]]
+}