Upgrade to golang protobuf api v2

Major operations:
 * Fix the go_package entries to be consistent, as the new tool
   complains when it doesn't have a '/'.
 * Regenerate with the new protoc-gen-go tool.
 * github.com/golang/protobuf -> google.golang.org/protobuf
 * proto.[Un]MarshalText -> prototext.[Un]Marshal

Change-Id: Ie1147bd2457fafb66ba555461b3bf14f0561a25d

scripts/microfactory.bash

@@ -59,7 +59,7 @@ function soong_build_go
     BUILDDIR=$(getoutdir) \
       SRCDIR=${TOP} \
       BLUEPRINTDIR=${TOP}/build/blueprint \
-      EXTRA_ARGS="-pkg-path android/soong=${TOP}/build/soong -pkg-path github.com/golang/protobuf=${TOP}/external/golang-protobuf" \
+      EXTRA_ARGS="-pkg-path android/soong=${TOP}/build/soong -pkg-path google.golang.org/protobuf=${TOP}/external/golang-protobuf" \
       build_go $@
 }