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/lint/python/pylint.mk b/makefiles/lint/python/pylint.mk
new file mode 100644
index 0000000..87ffb43
--- /dev/null
+++ b/makefiles/lint/python/pylint.mk
@@ -0,0 +1,95 @@
+# -*- makefile -*-
+# -----------------------------------------------------------------------
+# Copyright 2017-2023 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.
+# -----------------------------------------------------------------------
+
+$(if $(DEBUG),$(warning ENTER))
+
+##-------------------##
+##---]  GLOBALS  [---##
+##-------------------##
+.PHONY: lint-pylint lint-pylint-all lint-pylint-modified
+
+PYTHON_FILES      ?= $(error PYTHON_FILES= required)
+
+## -----------------------------------------------------------------------
+## Intent: Use the pylint command to perform syntax checking.
+##   o If UNSTABLE=1 syntax check all sources
+##   o else only check sources modified by the developer.
+## Usage:
+##   % make lint UNSTABLE=1
+##   % make lint-pylint-all
+## -----------------------------------------------------------------------
+ifndef NO-LINT-PYLINT
+  lint-pylint-mode := $(if $(have-python-files),modified,all)
+  lint        : lint-pylint
+  lint-pylint : lint-pylint-$(lint-pylint-mode)
+endif# NO-LINT-PYLINT
+
+## -----------------------------------------------------------------------
+## Intent: exhaustive pylint syntax checking
+## -----------------------------------------------------------------------
+
+# Construct: find . \( -name '__ignored__' -o -name dir -o name dir \)
+# pylint-find-filter := $(null)
+# pylint-find-filter += -name '__ignored__'#   # for alignment
+# pylint-find-filter += $(foreach dir,$(onf-excl-dirs),-o -name $(dir)))
+
+# pylint-find-filter := $(call gen-python-find-excl,onf-excl-dirs)
+# $(error pylint-find-filter := $(pylint-find-filter))
+lint-pylint-all: $(venv-activate-script)
+	$(MAKE) --no-print-directory lint-pylint-install
+
+	$(activate) && $(call gen-python-find-cmd) | $(xargs-n1) pylint
+#	    | $(xargs-n1-clean) yamllint --strict
+
+## -----------------------------------------------------------------------
+## Intent: check deps for format and python3 cleanliness
+## Note:
+##   pylint --py3k option no longer supported
+## -----------------------------------------------------------------------
+lint-pylint-modified: $(venv-activate-script)
+	$(MAKE) --no-print-directory lint-pylint-install
+
+	$(activate) && pylint $(PYTHON_FILES)
+
+## -----------------------------------------------------------------------
+## Intent:
+## -----------------------------------------------------------------------
+.PHONY: lint-pylint-install
+lint-pylint-install: $(venv-activate-script)
+	@echo
+	@echo "** -----------------------------------------------------------------------"
+	@echo "** python pylint syntax checking"
+	@echo "** -----------------------------------------------------------------------"
+	$(activate) && pip install --upgrade pylint
+	$(activate) && pylint --version
+	@echo
+
+## -----------------------------------------------------------------------
+## Intent: Display command usage
+## -----------------------------------------------------------------------
+help::
+	@echo '  lint-pylint          Syntax check python using the pylint command'
+  ifdef VERBOSE
+	@echo '  $(MAKE) lint-pylint PYTHON_FILES=...'
+	@echo '  lint-pylint-modified  pylint checking: only modified'
+	@echo '  lint-pylint-all       pylint checking: exhaustive'
+	@echo '  lint-pylint-install   Install the pylint command'
+  endif
+
+$(if $(DEBUG),$(warning LEAVE))
+
+# [EOF]