Add art_defaults to dexlayout

The build rule defaults for dexlayout targets didn't include defaults
from the ART project.  Because of this ART_TARGET_* weren't defined,
among other problems

Bug: 35800981
Test: make -j 40 test-art-host
Change-Id: Ic528bfc6b622fa9b4f5c0ddf883f15912641b720
diff --git a/dexlayout/Android.bp b/dexlayout/Android.bp
index e26d051..4b65c52 100644
--- a/dexlayout/Android.bp
+++ b/dexlayout/Android.bp
@@ -14,6 +14,7 @@
 
 art_cc_defaults {
     name: "libart-dexlayout-defaults",
+    defaults: ["art_defaults"],
     host_supported: true,
     srcs: [
         "dexlayout.cc",