Shove the tests into a different file

Also add descriptions because those are nice

Change-Id: I2d0480acf17af2700c8b7fb7228203e16a068f6b
diff --git a/libs/hwui/Android.mk b/libs/hwui/Android.mk
index cc0943f..eaade34 100644
--- a/libs/hwui/Android.mk
+++ b/libs/hwui/Android.mk
@@ -209,6 +209,7 @@
 
 LOCAL_SRC_FILES += \
     tests/TestContext.cpp \
+    tests/TreeContentAnimation.cpp \
     tests/main.cpp
 
 include $(BUILD_EXECUTABLE)