Build metrics_dump tool in Android.

Replace Makefile with Android.bp.
Remove duplication of protos in proto directory.

Since we are now building the metrics_dump tool
under Android, use frameworks metrics.proto
directly. Also, reference cdm's wv_metrics.proto
from the cdm directory instead of creating a
subset in proto directory.

bug: 161783052
bug: 170607430

Test: build
  m -j128 metrics_dump
Test: metrics_dump [bugreport from adt-3-r.zip]
Test: metrics_dump [bugreport from sabrina-q.gz]
Test: metrics_dump --widevine [adb shell dumpsys media.metrics output]
Change-Id: I82c7e723453ac2a6335cb2bb732a376d535b9ea3

libwvdrmengine/tools/metrics_dump/src/base64decode.cpp

@@ -4,12 +4,12 @@
 //
 // simple base64 decoder
 
+#include "base64decode.h"
+
 #include <iostream>
 #include <memory>
 #include <string>
 
-#include "base64decode.h"
-
 namespace base64 {
 
 using namespace std;