Add buffer.cc and platform_handle.cc to mojo build

Bug: none
Test: builds

Change-Id: I5eaf2de1409905e1147c66453b4b25653ad963f2
diff --git a/Android.mk b/Android.mk
index e25dbc6..f2f18cb 100644
--- a/Android.mk
+++ b/Android.mk
@@ -154,6 +154,8 @@
 	mojo/public/cpp/bindings/lib/validation_context.cc \
 	mojo/public/cpp/bindings/lib/validation_errors.cc \
 	mojo/public/cpp/bindings/lib/validation_util.cc \
+	mojo/public/cpp/system/buffer.cc \
+	mojo/public/cpp/system/platform_handle.cc \
 	mojo/public/cpp/system/watcher.cc \
 
 LOCAL_CFLAGS := \