Added AspectRatioTests CTS tests.

For testing android:maxAspectRatio API.

Test: cts/.../run-test CtsAppTestCases android.app.cts.AspectRatioTests
Bug: 33205955
Bug: 35810513
Change-Id: I6c29cbf173dc70ef03e25d935eb6e9922db27ffc
diff --git a/tests/app/Android.mk b/tests/app/Android.mk
index 2aab868..bb1dc10 100644
--- a/tests/app/Android.mk
+++ b/tests/app/Android.mk
@@ -34,6 +34,7 @@
 LOCAL_SRC_FILES := \
     $(call all-java-files-under, src) \
     $(call all-java-files-under, app2/src) \
+    $(call all-java-files-under, appSdk25/src) \
 
 # Tag this module as a cts test artifact
 LOCAL_COMPATIBILITY_SUITE := cts