configure: fix check for gettext

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
(transplanted from dc2943c987756c9bd928c1989843d4beb8cfc184)

 #!/bin/sh

 set -e

 printf "Running autoconf...\n"

 autoconf -Wall --force

 printf "Done. You may now run:\n    ./configure\n"