Add a repository-specific configuration file for git-buildpackage to
avoid having to pass options to it every time gbp is run.

This reverts commit 10fc5402.

fixes #332

Thanks to George Cho for coming up with a fix.
https://www.swig.org/Doc4.0/Perl5.html#Perl5_nn9

fixes
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=51488&sort=-opened&can=1&q=proj%3Agrok