Add a very simple helper function to log slow functions.

Change-Id: I2e2e072206d02b572a330dd25857c161b5b563bf
diff --git a/libs/utils/Android.mk b/libs/utils/Android.mk
index ddfb83e..c9f8fd4 100644
--- a/libs/utils/Android.mk
+++ b/libs/utils/Android.mk
@@ -26,6 +26,7 @@
 	FileMap.cpp \
 	Flattenable.cpp \
 	LinearTransform.cpp \
+	Log.cpp \
 	PropertyMap.cpp \
 	RefBase.cpp \
 	SharedBuffer.cpp \