package/ltris: fix linking with intl

package/ltris: fix linking with intl

ltris doen't build with (e)glibc toolchain since commit 454a41016f2f074b69e2c677f4749c213c653e86
when gettext package is selected.

With (e)glibc libintl is provided by the libc whereas with uClibc it's provided by gettext.

Linking with intl is only needed if the toolchain needs gettext and locale is set.

Fixes:
http://autobuild.buildroot.net/results/821/82128cb9f5cd6ae2595a8302462f1b5719dad9f7/build-end.log

Signed-off-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>