libwebm: Update Android build

- Change to libwebm.
- Add muxer support.
- Remove sample app.

Change-Id: I39c31ecbff573f86214e85b3ac08e0dcdfe22ae2

Android.mk

@@ -1,13 +1,10 @@
 LOCAL_PATH:= $(call my-dir)
 
 include $(CLEAR_VARS)
-LOCAL_MODULE:= libmkvparser
+LOCAL_MODULE:= libwebm
 LOCAL_SRC_FILES:= mkvparser.cpp \
-                  mkvreader.cpp
+                  mkvreader.cpp \
+                  mkvmuxer.cpp \
+                  mkvmuxerutil.cpp \
+                  mkvwriter.cpp
 include $(BUILD_STATIC_LIBRARY)
-
-include $(CLEAR_VARS)
-LOCAL_MODULE:= mkvparser
-LOCAL_SRC_FILES:= sample.cpp
-LOCAL_STATIC_LIBRARIES:= libmkvparser
-include $(BUILD_EXECUTABLE)