xapp_xinput: add missing dependencies

Following the big X.org bump, a few dependencies were missing in the
xapp_xinput package.

Fixes:
http://autobuild.buildroot.org/results/7e4ebd4dd47f49bcd4d225b17fbbc8b211e5201a/build-end.log

.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>