VOL-4977 - Failure in voltha-protos verification job.

Makefile
makefiles/consts.mk
makefiles/include.mk
virtualenv.mk
requirements.txt
--------------------
  o Added library makefiles from repo:onf-make to handle virtualenv setup/removal.
  o go-clean - augment clean rule, current behavior leaves directory unbuildable.

makefiles/docker/include.mk
---------------------------
  o Replace inlined copies of docker cli arguments with macros: is-stdin, docker-run, etc.
  o Moved docker command wrappers: PROTOC, etc into docker/include.mk

makefiles/help/*.mk
-------------------
  o Update and align makefile target help text.

Change-Id: Ifcf72e8081efc6e0d828ee4b1b96c66a219a39b9
diff --git a/makefiles/lint/makefile.mk b/makefiles/lint/makefile.mk
index 61de008..3cf41d2 100644
--- a/makefiles/lint/makefile.mk
+++ b/makefiles/lint/makefile.mk
@@ -37,6 +37,6 @@
 ## -----------------------------------------------------------------------
 ## -----------------------------------------------------------------------
 help ::
-	@echo '  lint-make                     Syntax check [Mm]akefile and *.mk'
+	@echo '  lint-make                    Syntax check [Mm]akefile and *.mk'
 
 # [EOF]