Release Android Runtime APEX module.

Introduce a release Android Runtime APEX module
(`com.android.runtime.release`), containing only the essential parts
of the runtime (i.e. without debug variants nor tools). This lighter
Runtime APEX package is intended for user builds as well as for
storage-constrained devices (like marlin and sailfish).

Rename the original Android Runtime APEX module (which also contains
debug variants and tools) as `com.android.runtime.debug`, and include
it in userdebug and eng builds (except configured otherwise).

Also introduce phony package (build target) `com.android.runtime` as
an alias for module `com.android.runtime.release` (for now).

Test: make com.android.runtime
Test: make com.android.runtime.release
Test: make com.android.runtime.debug
Test: art/build/apex/runtests.sh
Bug: 113373927
Change-Id: I27a50aee9d83c8c3a9bd38636022e9f5335a2a0d
diff --git a/Android.mk b/Android.mk
index b9f6170..d639220 100644
--- a/Android.mk
+++ b/Android.mk
@@ -326,6 +326,17 @@
 
 
 #######################
+# Android Runtime APEX.
+
+include $(CLEAR_VARS)
+LOCAL_MODULE := com.android.runtime
+# TODO: Select the debug module (`com.android.runtime.debug`) for
+# userdebug and eng products.
+LOCAL_REQUIRED_MODULES := com.android.runtime.release
+include $(BUILD_PHONY_PACKAGE)
+
+
+#######################
 # Fake packages for ART
 
 # The art-runtime package depends on the core ART libraries and binaries. It exists so we can