Ignore autotools generated files.

Signed-off-by: Michael Lippautz <michael.lippautz@gmail.com>
Add autogen.sh, used to regenerate autotools files.

Signed-off-by: Michael Lippautz <michael.lippautz@gmail.com>
gitignore: Add autotools generated files.

Signed-off-by: Michael Lippautz <michael.lippautz@gmail.com>