Improve target coverage for the reuse license checker.

misc
----
  o Copyright notice update from onf v1 to onf v1.1

makefiles/etc/utils.mk
----------------------
  o Function path-by-makefilepath-by-makefile():
    - Replace $(subst include.mk) with $(dir) so path construction becomes generic.
    - Added wrapper function genpath-makefiles() to improve call usability.

makefiles/lint/license/include.mk
makefiles/lint/license/reuse.mk
makefiles/lint/license/install.mk
---------------------------------
  o Added requirements.txt for reuse tool install (ability to vesion and freeze for release).
  o Define command var REUSE= so local devs can override.
  o Added banner-{enter,leave} for logfile visibility.

makefiles/lint/license/include.mk

makefiles/lint/license/help.mk
------------------------------
  o Document a few missing targets for 'make help' and 'make lint-reuse-help'.

[HOWTO: test]
-------------
% make sterile
% make venv                 # install virtualenv
% make lint-reuse-install

% make sterile
% make lint-reuse-version

% make sterile
% make lint-reuse

Change-Id: I91f4789981f3d3c5bc744d2db99374f9790e3b98
diff --git a/makefiles/lint/license/reuse.mk b/makefiles/lint/license/reuse.mk
index 408a329..306ab76 100644
--- a/makefiles/lint/license/reuse.mk
+++ b/makefiles/lint/license/reuse.mk
@@ -18,11 +18,15 @@
 ##-------------------##
 ##---]  GLOBALS  [---##
 ##-------------------##
+$(call genpath-makefiles,lint-reuse-req-txt,requirements.txt)
+# $(error lint-reuse-req-text=$(lint-reuse-req-txt))
 
 ##-------------------##
 ##---]  TARGETS  [---##
 ##-------------------##
 ifndef NO-LINT-REUSE
+#  lint-reuse-mode := $(if $(have-reuse-files),mod,all)
+#  lint : lint-reuse-$(lint-reuse-mode)
   lint : lint-reuse
 endif
 
@@ -33,7 +37,10 @@
 ## -----------------------------------------------------------------------
 ## Intent: Perform a lint check on makefile sources
 ## -----------------------------------------------------------------------
-lint-reuse:
-	reuse --root . lint
+lint-reuse : lint-reuse-version
+
+	$(call banner-enter,Target $@)
+	$(activate) && $(REUSE) --root . lint
+	$(call banner-enter,Target $@)
 
 # [EOF]