Support to build static Java library with Android resource

Bug: 5714516

The rationale behind this change:
- the library is compiled into a jar file, but its R class is generated
  making the constant not constant (static, not final static) (aapt
  option --non-constant-id). Also the jar file does not contain the R
  class.
- this allows the integer value to not be inlined in the compiled
  class files. Note that this prevents using switch statements.
- the main project use this jar file as a normal static library: it will
  add all the class files except the R.class.
- the main project uses the library res folder as a resource
  folder with lower priority than the main project (basically the
  main project is an overlay. This is accomplished using aapt's
  --auto-add-overlay to handle resources only in the main project
  (which the normal overlay mechanism doesn't allow).
- the main project creates R classes in the main project's
  package but also in the library's package. This is done with
  aapt's --extra-packages which accept as many packages as
  needed, separated by a :.
- manifest merging is not done yet, so
  activities/services/permissions/etc... have to be manually declared in
  the main app.

To use a static library with Android resource in your app,
1. Add the library's resource dir to your app as an overlay:
LOCAL_RESOURCE_DIR := <app_resource_dir> <static_library_resource_dirs>
2. Set the proper aapt flags:
LOCAL_AAPT_FLAGS := <apps_own_flags> --auto-add-overlay \
  --extra-packages <lib1_package_name>:<lib2_package_name>:...

Change-Id: Ifb4d2300b952ea4aaee74da1bb0c6c72ea0698a3

core/static_java_library.mk

@@ -21,5 +21,75 @@
 
 LOCAL_UNINSTALLABLE_MODULE := true
 LOCAL_IS_STATIC_JAVA_LIBRARY := true
+
+# Hack to build static Java library with Android resource
+# See bug 5714516
+all_resources :=
+ifdef LOCAL_RESOURCE_DIR
+all_resources := $(strip \
+    $(foreach dir, $(LOCAL_RESOURCE_DIR), \
+      $(addprefix $(dir)/, \
+        $(patsubst res/%,%, \
+          $(call find-subdir-assets,$(dir)) \
+        ) \
+      ) \
+    ))
+endif
+
 include $(BUILD_SYSTEM)/java_library.mk
+
+ifneq (,$(all_resources))
+R_file_stamp := $(LOCAL_INTERMEDIATE_SOURCE_DIR)/R.stamp
+
+ifeq ($(strip $(LOCAL_MANIFEST_FILE)),)
+LOCAL_MANIFEST_FILE := AndroidManifest.xml
+endif
+full_android_manifest := $(LOCAL_PATH)/$(LOCAL_MANIFEST_FILE)
+
+framework_res_package_export :=
+framework_res_package_export_deps :=
+# Please refer to package.mk
+ifneq ($(LOCAL_NO_STANDARD_LIBRARIES),true)
+ifneq ($(filter-out current,$(LOCAL_SDK_RES_VERSION)),)
+framework_res_package_export := \
+    $(HISTORICAL_SDK_VERSIONS_ROOT)/$(LOCAL_SDK_RES_VERSION)/android.jar
+framework_res_package_export_deps := $(framework_res_package_export)
+else
+framework_res_package_export := \
+    $(call intermediates-dir-for,APPS,framework-res,,COMMON)/package-export.apk
+framework_res_package_export_deps := \
+    $(dir $(framework_res_package_export))src/R.stamp
+endif
+endif
+
+$(R_file_stamp): PRIVATE_MODULE := $(LOCAL_MODULE)
+# add --non-constant-id to prevent inlining constants.
+$(R_file_stamp): PRIVATE_AAPT_FLAGS := $(LOCAL_AAPT_FLAGS) --non-constant-id
+$(R_file_stamp): PRIVATE_SOURCE_INTERMEDIATES_DIR := $(LOCAL_INTERMEDIATE_SOURCE_DIR)
+$(R_file_stamp): PRIVATE_ANDROID_MANIFEST := $(full_android_manifest)
+$(R_file_stamp): PRIVATE_RESOURCE_PUBLICS_OUTPUT := $(intermediates.COMMON)/public_resources.xml
+$(R_file_stamp): PRIVATE_RESOURCE_DIR := $(LOCAL_RESOURCE_DIR)
+$(R_file_stamp): PRIVATE_AAPT_INCLUDES := $(framework_res_package_export)
+ifneq (,$(filter-out current, $(LOCAL_SDK_VERSION)))
+$(R_file_stamp): PRIVATE_DEFAULT_APP_TARGET_SDK := $(LOCAL_SDK_VERSION)
+else
+$(R_file_stamp): PRIVATE_DEFAULT_APP_TARGET_SDK := $(DEFAULT_APP_TARGET_SDK)
+endif
+$(R_file_stamp): PRIVATE_ASSET_DIR :=
+$(R_file_stamp): PRIVATE_PROGUARD_OPTIONS_FILE :=
+$(R_file_stamp): PRIVATE_MANIFEST_PACKAGE_NAME :=
+$(R_file_stamp): PRIVATE_MANIFEST_INSTRUMENTATION_FOR :=
+
+$(R_file_stamp) : $(all_resources) $(full_android_manifest) $(AAPT) $(framework_res_package_export_deps)
+	@echo "target R.java/Manifest.java: $(PRIVATE_MODULE) ($@)"
+	$(create-resource-java-files)
+	$(hide) find $(PRIVATE_SOURCE_INTERMEDIATES_DIR) -name R.java | xargs cat > $@
+
+$(LOCAL_BUILT_MODULE): $(R_file_stamp)
+ifneq ($(full_classes_jar),)
+$(full_classes_compiled_jar): $(R_file_stamp)
+endif
+
+endif  # $(all_resources) not empty
+
 LOCAL_IS_STATIC_JAVA_LIBRARY :=