Makefile improvements

.gitignore
----------
  o Added .venv/ so git will ignore local python virtual env.

Makefile
--------
  o Update copyright notice to latest syntax (w/SPDX tokens).
  o Remove dup go-protos and java-protos as build target dependencies,
    build depends on protos which depends on {build,go}-protos.
  o Changed "python ./setup.py sdist" to "$(activate) && python ...",
    difference: cmd[1] is system interpreter, cmd[2] is installed
    virtualenv interpreter used by all other commands.

makefiles/help/include.mk
makefiles/help/go.mk
makefiles/help/java.mk
makefiles/help/python.mk
------------------------
  o Help target formatting and cleanup.
  o Not all language targets {go,java,python}-* were documented.

Change-Id: I752ec3f38ae28f868934f36460e5fd3f588bd810
Signed-off-by: Eric Ball <eball@linuxfoundation.org>
diff --git a/makefiles/include.mk b/makefiles/include.mk
index ecf52d5..e35fe5d 100644
--- a/makefiles/include.mk
+++ b/makefiles/include.mk
@@ -40,7 +40,7 @@
 
 include $(MAKEDIR)/golang/include.mk
 
-include $(MAKEDIR)/help/variables.mk
+# include $(MAKEDIR)/help/variables.mk
 include $(MAKEDIR)/lint/include.mk
 include $(MAKEDIR)/todo.mk