Makefile library merge with onf-make and voltha-lib-go

makefiles/
----------
  o Import standalone makefile directories to checkin smaller parts of a mega patch.
  o Build out directory hierarchy by topic and feature.

makefiles/lint/yaml/
--------------------
  o Pull in logic evolved in repo:voltha-lib-go.
  o Refactoring: support special snowflake targets by repository.
  o ci-management and voltha-lib-go use distinct yamllint.conf files.
  o Separate until there is time to review and consolidate.
  o Added deps for on-demand local install of yamllint.
    - requirements.txt could be used but every build would incur overhead.

Makefile
--------
  o Use latest syntax from repo:onf-make.
  o No need to set path variables, makefiles/include.mk can infer them.
  o Added a help target to explicitly display targets and suggestions.
  o Logic is bundled in libraries and use of 'make help' is not well known.

Change-Id: Id8eba6f914a7bfe9a31637901bd8fb78a387e0c2
diff --git a/makefiles/utils/include.mk b/makefiles/utils/include.mk
new file mode 100644
index 0000000..5a7678f
--- /dev/null
+++ b/makefiles/utils/include.mk
@@ -0,0 +1,29 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2022-2023 Open Networking Foundation (ONF) and the ONF Contributors
+#
+# 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.
+#
+# SPDX-FileCopyrightText: 2022-2023 Open Networking Foundation (ONF) and the ONF Contributors
+# SPDX-License-Identifier: Apache-2.0
+# -----------------------------------------------------------------------
+
+$(if $(DEBUG),$(warning ENTER))
+
+# usage: $(call if-not,false,5)
+if-not = $(info 1=$(1), 2=$(2), 3=$(3))\
+  $(if $(1),$(null),$(2))
+
+$(if $(DEBUG),$(warning LEAVE))
+
+# [EOF]
diff --git a/makefiles/utils/test/makefile b/makefiles/utils/test/makefile
new file mode 100644
index 0000000..a148cfa
--- /dev/null
+++ b/makefiles/utils/test/makefile
@@ -0,0 +1,9 @@
+# -*- makefile -*-
+
+include ../include.mk
+
+all:
+
+test ::
+	@echo "Testing if-not"
+	@echo $(call if-not,$(null),true,false)