Support dexpreopt against the primary boot image.

Test: taimen-userdebug boots when built with
      DEXPREOPT_USE_ART_IMAGE=true
Bug: 119800099
Change-Id: I1c0860de87a0280d93a63b9135d071c595f1d925
diff --git a/core/dex_preopt_config.mk b/core/dex_preopt_config.mk
index 5dd5505..cd73843 100644
--- a/core/dex_preopt_config.mk
+++ b/core/dex_preopt_config.mk
@@ -73,6 +73,7 @@
   $(call add_json_bool, DisablePreopt,                      $(call invert_bool,$(and $(filter true,$(PRODUCT_USES_DEFAULT_ART_CONFIG)),$(filter true,$(WITH_DEXPREOPT)))))
   $(call add_json_list, DisablePreoptModules,               $(DEXPREOPT_DISABLED_MODULES))
   $(call add_json_bool, OnlyPreoptBootImageAndSystemServer, $(filter true,$(WITH_DEXPREOPT_BOOT_IMG_AND_SYSTEM_SERVER_ONLY)))
+  $(call add_json_bool, UseArtImage,                        $(filter true,$(DEXPREOPT_USE_ART_IMAGE)))
   $(call add_json_bool, GenerateApexImage,                  $(filter true,$(DEXPREOPT_GENERATE_APEX_IMAGE)))
   $(call add_json_bool, UseApexImage,                       $(filter true,$(DEXPREOPT_USE_APEX_IMAGE)))
   $(call add_json_bool, DontUncompressPrivAppsDex,          $(filter true,$(DONT_UNCOMPRESS_PRIV_APPS_DEXS)))