tools: add flag to avoid git pull during tarball create

it breaks jenkins scripts because jenkins fetches the branch and disconnects it from the repo.
hence git pull fails
(cherry picked from commit 81917412a86bd8bce7adf17871b6ccaf17770a32)

Conflicts:
	contrib/dist/make_dist_tarball
Merge pull request #128 from miked-mellanox/topic/fix_makedist

port makedist fixes from master