Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/jenkins/buildcmds/pull_request.sh

Index: third_party/protobuf/jenkins/buildcmds/pull_request.sh
diff --git a/third_party/protobuf/jenkins/buildcmds/pull_request.sh b/third_party/protobuf/jenkins/buildcmds/pull_request.sh
new file mode 100755
index 0000000000000000000000000000000000000000..01fda798586dafb78068daa06739fff350adbaee
--- /dev/null
+++ b/third_party/protobuf/jenkins/buildcmds/pull_request.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+#
+# This is the top-level script we give to Jenkins as the entry point for
+# running the "pull request" project:
+#
+#   https://grpc-testing.appspot.com/view/Protocol%20Buffers/job/protobuf_pull_request/
+#
+# This script selects a specific Dockerfile (for building a Docker image) and
+# a script to run inside that image.  Then we delegate to the general
+# build_and_run_docker.sh script.
+
+export DOCKERFILE_DIR=jenkins/docker
+export DOCKER_RUN_SCRIPT=jenkins/pull_request_in_docker.sh
+export OUTPUT_DIR=testoutput
+./jenkins/build_and_run_docker.sh