Add flags needed to switch Jack to 1.8 for CTS targets

When linking against .jack files that contain 1.8 language
features Jack (currently) requires -D jack.java.source.version=1.8.

"core-tests" includes 1.8 language features.

Bug: 27113322
Bug: 26953739
Change-Id: Ib9ceaadafc9c1d41ff137c48111ad3b060f7e248
diff --git a/media/tests/MediaFrameworkTest/Android.mk b/media/tests/MediaFrameworkTest/Android.mk
index 6b9fdb6..7c1142b 100644
--- a/media/tests/MediaFrameworkTest/Android.mk
+++ b/media/tests/MediaFrameworkTest/Android.mk
@@ -7,6 +7,8 @@
 
 LOCAL_JAVA_LIBRARIES := android.test.runner
 
+LOCAL_JAVA_LANGUAGE_VERSION := 1.8
+
 LOCAL_STATIC_JAVA_LIBRARIES := easymocklib \
     mockito-target \
     core-tests \