VOL-4917 - voltha-go build and test problems.

  o Update copyright notice.
  o Added a few common makefile libraries.
  o Added todo.mk to document a few future-fix items.
  o Added versions.mk used to display build tools and versions.
  o Added comments and banners to delimit logic and identify log output.
  o Fixed coverage target, git test -coverprofile requires a disk file.
  o Strange: 'go mod vendor' will remove vendor/ but the directory is
    under revision control.  [TODO] Delete or checkout from a central repo.
  o Split long lines with line continuation at shell pipe.
  o Replace inlined rm -rf calls with make builtin $(RM) -r
  o Refacor test log names into macros to shorten logic line length.

  o Update copyright notice.
  o Inline --no-cache with apk calls, networking problems surfaced while
    running "make build/test" while disconnected from the VPN.
  o Copy stub go-test-coverage.out file to the docker image, go test
    -coverprofile was failing w/o a file on disk.
  o Testing reported a "could not create cpu profile" error.  Create a pull
    request for feedback to see if this is a lingering coverage problem or
    my laptop cpu is unknown and contributing.

Change-Id: I84724682cfd9dbcd08990cef382338f005261184
diff --git a/makefiles/consts.mk b/makefiles/consts.mk
new file mode 100644
index 0000000..c34d119
--- /dev/null
+++ b/makefiles/consts.mk
@@ -0,0 +1,28 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2022 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,
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# -----------------------------------------------------------------------
+null         :=#
+space        :=$(null) $(null)
+dot          :=.
+HIDE         ?=@
+# use bash for pusdh/popd and quick failures.
+# virtual env(s) activate has undefined vars so no -u
+#   ^---+ verify this is still true
+export SHELL := bash -e -o pipefail
+# [EOF]