Fix to avoid warnings about a "broken pipe".

Scripts/developer_scripts/create_cgal_test_with_cmake

@@ -146,7 +146,7 @@ EOF
       tmp=`basename $file .C`
       tmp=`basename $tmp .cpp`
       cat <<EOF
-if  \${MAKE_CMD} -f Makefile help | grep -q $tmp; then 
+if  \${MAKE_CMD} -f Makefile help | grep "$tmp" > /dev/null; then 
   compile_and_run $tmp
   NEED_CLEAN=y
 fi