Fix the tools/art script about the ISA-specific dalvik cache.

Bug: 14470552
Change-Id: I71367052d2a5f0dcf66cf2dfdbc260aff4ac952e
diff --git a/tools/art b/tools/art
index c9c0d4f..e3f409c 100755
--- a/tools/art
+++ b/tools/art
@@ -48,7 +48,7 @@
 ANDROID_HOST_OUT=$PROG_DIR/..
 ANDROID_DATA=$PWD/android-data$$
 
-mkdir -p $ANDROID_DATA/dalvik-cache
+mkdir -p $ANDROID_DATA/dalvik-cache/{x86,x86_64}
 ANDROID_DATA=$ANDROID_DATA \
   ANDROID_ROOT=$ANDROID_HOST_OUT \
   LD_LIBRARY_PATH=$ANDROID_HOST_OUT/lib \