ART change: Script is using function(), which is bash specific.

Change-Id: Ieb2a9674c95aafadbdb26c060f186f3f2d0f5e15
diff --git a/tools/art b/tools/art
index 6db8cd0..aa53a39 100755
--- a/tools/art
+++ b/tools/art
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 #
 # Copyright (C) 2011 The Android Open Source Project
 #