Add build-containerd.sh to build containerd from existing repo

Signed-off-by: Lantao Liu <lantaol@google.com>

hack/install/utils.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+
+# Copyright 2018 The containerd Authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+source $(dirname "${BASH_SOURCE[0]}")/../utils.sh
+
+# DESTDIR is the dest path to install dependencies.
+DESTDIR=${DESTDIR:-"/"}
+# Convert to absolute path if it's relative.
+if [[ ${DESTDIR} != /* ]]; then
+  DESTDIR=${ROOT}/${DESTDIR}
+fi
+
+# NOSUDO indicates not to use sudo during installation.
+NOSUDO=${NOSUDO:-false}
+SUDO="sudo"
+if ${NOSUDO}; then
+  SUDO=""
+fi
+
+# BUILDTAGS are bulid tags for runc and containerd.
+BUILDTAGS=${BUILDTAGS:-seccomp apparmor}
+
+# checkout_repo checks out specified repository
+# and switch to specified  version.
+# Varset:
+# 1) Pkg name;
+# 2) Version;
+# 3) Repo name;
+checkout_repo() {
+  local -r pkg=$1
+  local -r version=$2
+  local -r repo=$3
+  path="${GOPATH}/src/${pkg}"
+  if [ ! -d ${path} ]; then
+    mkdir -p ${path}
+    git clone https://${repo} ${path}
+  fi
+  cd ${path}
+  git fetch --all
+  git checkout ${version}
+}