Introduce Make variables for the various Runtime APEX names.

Test: make systemimage (with user lunch target)
Test: make systemimage (with userdebug/eng lunch target)
Test: art/build/apex/runtests.sh
Bug: 129534335
Change-Id: I69a06acc777acba17deb5e32061d1099ae82beaf
diff --git a/build/Android.common_path.mk b/build/Android.common_path.mk
index 625444f..b0bd7fd 100644
--- a/build/Android.common_path.mk
+++ b/build/Android.common_path.mk
@@ -147,4 +147,12 @@
 ART_HOST_EXECUTABLES += $(foreach name,$(ART_CORE_DEBUGGABLE_EXECUTABLES),$(name)d-host)
 endif
 
+# Release Runtime APEX, included by default in "user" builds.
+RELEASE_RUNTIME_APEX := com.android.runtime.release
+# Debug Runtime APEX, included by default in "userdebug" and "eng"
+# builds and used in ART device testing and benchmarking.
+DEBUG_RUNTIME_APEX := com.android.runtime.debug
+# Testing Runtime APEX (not used yet).
+TESTING_RUNTIME_APEX := com.android.runtime.testing
+
 endif # ART_ANDROID_COMMON_PATH_MK