UBUNTU: [Packaging] sort ABI files with C.UTF-8 locale

UBUNTU: [Packaging] sort ABI files with C.UTF-8 locale

BugLink: https://bugs.launchpad.net/bugs/1712345
Whenever we update the ABI files, the files may be sorted in a different
order, even though their contents are the same. That happens because the
system updating the ABI files may use a different locale than the one
that was used previously.

Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Acked-by: Marcelo Cerri <marcelo.cerri@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>