Do not exclude our sources from `git archive`
Do not exclude our sources from `git archive`

Revert commit 7e293acc (Exclude from source archives files specific to
Git work tree, 2012-03-02).  Projects may want to use `git archive` to
import GitSetup as a subtree snapshot instead of merging our history.
Importing projects can add the exclusion to their own `.gitattributes`.

kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix