Make the tools/art script appear to work from any directory.

This isn't the real fix, and it means that your oatexec will be running
from $(ANDROID_BUILD_TOP) rather than your current directory, but it lets
me use a modified vogar that just calls "art" instead of "dalvikvm", as
long as I use absolute paths.

Change-Id: Iac35fcd2114316a06780b4f1f27eee9fbe95282d
diff --git a/tools/art b/tools/art
index 1e983c0..4f419b2 100755
--- a/tools/art
+++ b/tools/art
@@ -35,6 +35,7 @@
 
 unset ANDROID_PRODUCT_OUT # avoid defaulting dex2oat --host-prefix to target output
 mkdir -p /tmp/android-data/art-cache
+cd $ANDROID_BUILD_TOP
 ANDROID_DATA=/tmp/android-data\
  ANDROID_ROOT=$ANDROID_HOST_OUT\
  LD_LIBRARY_PATH=$ANDROID_HOST_OUT/lib\