CI: Do not `mkdir 2`.

Change-Id: Ib7377d26a6c98b38bad463f47c84f1875ac84eb7

tests/CI/buildAsterisk.sh

@@ -26,10 +26,10 @@ gen_mods() {
 	done
 }
 
-[ x"$OUTPUT_DIR" != x ] && mkdir -p "$OUTPUT_DIR" 2&> /dev/null
+[ x"$OUTPUT_DIR" != x ] && mkdir -p "$OUTPUT_DIR" 2> /dev/null
 
 if [ x"$CACHE_DIR" != x ] ; then
-	mkdir -p $CACHE_DIR/sounds $CACHE_DIR/externals 2&> /dev/null
+	mkdir -p $CACHE_DIR/sounds $CACHE_DIR/externals 2> /dev/null
 fi
 
 if [ ${CCACHE_DISABLE:-0} -ne 1 ] ; then