vendor: Update github.com/gogo/protobuf, keeping all files

gvt fetch -a, because we need the protobuf files etc for regeneration

vendor/github.com/gogo/protobuf/install-protobuf.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env bash
+
+set -ex
+
+die() {
+    echo "$@" >&2
+    exit 1
+}
+
+cd /home/travis
+
+case "$PROTOBUF_VERSION" in
+2*)
+    basename=protobuf-$PROTOBUF_VERSION
+    wget https://github.com/google/protobuf/releases/download/v$PROTOBUF_VERSION/$basename.tar.gz
+    tar xzf $basename.tar.gz
+    cd protobuf-$PROTOBUF_VERSION
+    ./configure --prefix=/home/travis && make -j2 && make install
+    ;;
+3*)
+    basename=protoc-$PROTOBUF_VERSION-linux-x86_64
+    wget https://github.com/google/protobuf/releases/download/v$PROTOBUF_VERSION/$basename.zip
+    unzip $basename.zip
+    ;;
+*)
+    die "unknown protobuf version: $PROTOBUF_VERSION"
+    ;;
+esac
+
+
+
+