vendor: Mega update all dependencies

GitHub-Pull-Request: https://github.com/syncthing/syncthing/pull/4080

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

@@ -1,29 +0,0 @@
-#!/usr/bin/env bash
-
-set -ex
-
-die() {
-    echo "$@" >&2
-    exit 1
-}
-
-case "$PROTOBUF_VERSION" in
-2*)
-    basename=protobuf-$PROTOBUF_VERSION
-    ;;
-3*)
-    basename=protobuf-cpp-$PROTOBUF_VERSION
-    ;;
-*)
-    die "unknown protobuf version: $PROTOBUF_VERSION"
-    ;;
-esac
-
-cd /home/travis
-
-wget https://github.com/google/protobuf/releases/download/v$PROTOBUF_VERSION/$basename.tar.gz
-tar xzf $basename.tar.gz
-
-cd protobuf-$PROTOBUF_VERSION
-
-./configure --prefix=/home/travis && make -j2 && make install