Collect and store proguard obfuscation dictionary files.

Collect and store proguard obfuscation dictionary files.
Only do this for apps_only build for now.

Bug: 9407666
Change-Id: I51c78bf0f42f959dc920de230e60e0f71ed0d0ea
diff --git a/core/main.mk b/core/main.mk
index 282d9c3..3af4306 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -819,6 +819,9 @@
     $(call dist-for-goals,apps_only, $(EMMA_META_ZIP))
   endif
 
+  $(PROGUARD_DICT_ZIP) : $(apps_only_installed_files)
+  $(call dist-for-goals,apps_only, $(PROGUARD_DICT_ZIP))
+
 .PHONY: apps_only
 apps_only: $(unbundled_build_modules)