config.h.in~ backup file in release tar balls

[igalic]

Describe the bug
The last two release tar balls contained a file config.h.in~, a backup file of config.h.in

To reproduce
Steps to reproduce the behavior:

1. download latest tar ball
2. extract
3. find config.h.in~

Expected behavior
that file should not exist.

System:

• Unbound version: 1.19.0

Additional information
noticed on FreeBSD vendor import of unbound: freebsd/freebsd-src@103ba50 (subsequently fixed: freebsd/freebsd-src@5aab39b )

[wcawijngaards]

The config.h.in~ backup file is likely created due to the change in the distribution generation script to use autoreconf, that then runs the additional script and creates the backup file. The fix removes the file if present from release tarballs. Thanks for noticing the superfluous file!