Make tests assume ANDROID_ROOT is not /system.

This is to enable better chroot-like testing.

Change-Id: I943c68b0ebcdab2f107f808b466ac694085255aa
diff --git a/tools/art b/tools/art
index 6c89a60..85e6e2f 100644
--- a/tools/art
+++ b/tools/art
@@ -92,6 +92,7 @@
 ANDROID_DATA=$ANDROID_DATA \
   ANDROID_ROOT=$ANDROID_ROOT \
   LD_LIBRARY_PATH=$LD_LIBRARY_PATH \
+  PATH=$ANDROID_ROOT/bin:$PATH \
   $invoke_with $ANDROID_ROOT/bin/$DALVIKVM $lib \
     -XXlib:$LIBART \
     -Ximage:$ANDROID_ROOT/framework/core.art \