Add android.test.base/stubs dependency

In preparation for the removal of the non-junit classes in the
android.test.base library from the android.jar this adds a dependency
on android.test.base/stubs to ensure this code will continue to
compile.

The following change descriptions were generated automatically and so
may be a little repetitive. They are provided to give the reviewer
enough information to check the comments match what has actually been
changed and check the reasoning behind the changes.

* tests/Android.mk
    Added 'android.test.base.stubs' to LOCAL_JAVA_LIBRARIES because
    messagingtests's will need them in order to compile once its
    classes are removed from the current SDK on which it currently
    depends.

Bug: 30188076
Test: make dist
Change-Id: Iabfb3c655897781ab3aee2b0dbf574d6048954a9

tests/Android.mk

@@ -32,7 +32,11 @@ LOCAL_CERTIFICATE := platform
 LOCAL_STATIC_JAVA_LIBRARIES := \
     mockito-target
 
-LOCAL_JAVA_LIBRARIES := android.test.mock.stubs android.test.runner.stubs
+LOCAL_JAVA_LIBRARIES := \
+    android.test.mock.stubs \
+    android.test.runner.stubs \
+    android.test.base.stubs \
+
 
 include $(BUILD_PACKAGE)