VOL-2629 Modified Makefile to use containerized tools.

Modified existing containers to build internally, rather than bind-mounting the whole project & running make targets.
This repo has C dependencies, which must be made available, which complicates the usage of containerized tools.  Some tool containers are augmented before use.
"build-" targets will continue to use locally installed golang.
"release-" targets will use containerized tools, and will cross-compile only bbsimctl.

Change-Id: I02c999a29361d26aa9198d1f03b2b050febfe954
diff --git a/build/ci/builder.Dockerfile b/build/ci/builder.Dockerfile
new file mode 100644
index 0000000..94ab871
--- /dev/null
+++ b/build/ci/builder.Dockerfile
@@ -0,0 +1,23 @@
+# Copyright 2020-present Open Networking Foundation
+#
+# 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.
+
+FROM golang:1.13.8-stretch
+
+RUN apt-get update && apt-get install -y \
+    build-essential libpcap-dev && \
+    mkdir -m 777 /.cache /go/pkg
+
+ENV CGO_ENABLED=1
+
+WORKDIR /app
\ No newline at end of file