ART: Fix soong defaults order

Defaults are prepended in order of their appearance. Move debug
defaults first.

Bug: 31098551
Test: m test-art-host
Change-Id: I9a64db34d0e398d336dac080c7234cad77b719ee
diff --git a/imgdiag/Android.bp b/imgdiag/Android.bp
index eaeb78e..9459bb5 100644
--- a/imgdiag/Android.bp
+++ b/imgdiag/Android.bp
@@ -64,8 +64,8 @@
 art_cc_binary {
     name: "imgdiagd",
     defaults: [
-        "imgdiag-defaults",
         "art_debug_defaults",
+        "imgdiag-defaults",
     ],
     shared_libs: [
         "libartd",