libinih: Update to version r55

libinih: Update to version r55

- Update from version r53 to r55
- Update of rootfile not required
- Changelog
   inih version 55
     Added "version" to meson.build config: #135 (but bumped up to 55 in a subsequent
      commit, for this release).
   inih version 54
     Mainly #134, adding the visibility symbols to the Meson build config, but also other
      small tweaks to tests and so on.

Signed-off-by: Adolf Belka <adolf.belka@ipfire.org>
Reviewed-by: Peter Müller <peter.mueller@ipfire.org>