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/.gitignore b/.gitignore
index 8a1cfba..f4317eb 100755
--- a/.gitignore
+++ b/.gitignore
@@ -25,3 +25,5 @@
 
 #editors
 .idea/
+
+.venv/
\ No newline at end of file