Re-enable dx support

This is a partial revert of commits:
858657366fa6 Remove support of disabling Jack.
3ae78612522e Remove javac support in host dex rules.
22313f2b2a4a Remove rules for building dex with dx

Test: builds
Change-Id: Ie12d743cbe978bdeb030910848b67f5945a4fec8
diff --git a/core/dpi_specific_apk.mk b/core/dpi_specific_apk.mk
index bcc5c18..1ca01d5 100644
--- a/core/dpi_specific_apk.mk
+++ b/core/dpi_specific_apk.mk
@@ -31,9 +31,15 @@
 $(built_dpi_apk): $(additional_certificates)
 $(built_dpi_apk): PRIVATE_ADDITIONAL_CERTIFICATES := $(additional_certificates)
 
+$(built_dpi_apk): PRIVATE_SOURCE_ARCHIVE :=
 ifneq ($(full_classes_jar),)
-$(built_dpi_apk): PRIVATE_JACK_INTERMEDIATES_DIR := $(intermediates.COMMON)/jack-rsc
 $(built_dpi_apk): PRIVATE_DEX_FILE := $(built_dex)
+ifndef LOCAL_JACK_ENABLED
+# Use the jarjar processed arhive as the initial package file.
+$(built_dpi_apk): PRIVATE_SOURCE_ARCHIVE := $(full_classes_jarjar_jar)
+else
+$(built_dpi_apk): PRIVATE_JACK_INTERMEDIATES_DIR := $(intermediates.COMMON)/jack-rsc
+endif # LOCAL_JACK_ENABLED
 $(built_dpi_apk): $(built_dex)
 else
 $(built_dpi_apk): PRIVATE_DEX_FILE :=
@@ -46,7 +52,9 @@
 $(built_dpi_apk) : $(AAPT)
 $(built_dpi_apk) : $(all_res_assets) $(jni_shared_libraries) $(full_android_manifest)
 	@echo "target Package: $(PRIVATE_MODULE) ($@)"
-	$(create-empty-package)
+	$(if $(PRIVATE_SOURCE_ARCHIVE),\
+	  $(call initialize-package-file,$(PRIVATE_SOURCE_ARCHIVE),$@),\
+	  $(create-empty-package))
 	$(add-assets-to-package)
 ifneq ($(jni_shared_libraries),)
 	$(add-jni-shared-libs-to-package)
@@ -56,8 +64,10 @@
 	$(if $(PRIVATE_EXTRA_JAR_ARGS),$(call add-java-resources-to,$@))
 else
 	$(add-dex-to-package)
+ifdef LOCAL_JACK_ENABLED
 	$(add-carried-jack-resources)
 endif
+endif
 	$(sign-package)
 
 # Set up global variables to register this apk to the higher-level dependency graph.