skip test if llvm-gcc is requires but not found on the path.
someone with llvm-gcc installed please test if the Codegen/function-attributes.c test isn't skip in your system. thanks.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@55871 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/TestRunner.sh b/test/TestRunner.sh
index 09b73d2..eed956e 100755
--- a/test/TestRunner.sh
+++ b/test/TestRunner.sh
@@ -68,6 +68,20 @@
     grep XFAIL $FILENAME
 fi
 
+if (grep -q "%llvmgcc" $FILENAME); then
+  if [ -z "$(llvm-gcc --version 2> /dev/null)" ]; then
+    IS_XFAIL=1
+    echo "llvm-gcc not found"
+  fi
+fi
+
+if (grep -q "%llvmgxx" $FILENAME); then
+  if [ -z "$(llvm-g++ --version 2> /dev/null)" ]; then
+    IS_XFAIL=1
+    echo "llvm-g++ not found"
+  fi
+fi
+
 /bin/sh $SCRIPT > $OUTPUT 2>&1
 SCRIPT_STATUS=$?