xfree86: Fix out of array bound access to xf86Entities

Signed-off-by: Łukasz Spintzyk <lukasz.spintzyk@synaptics.com>
(cherry picked from commit d66b7ec1)
3 jobs for port_fix_crash_in_1187 in 5 minutes and 26 seconds (queued for 1 second)
Status Job ID Name Coverage
  Docker Image
passed debian-testing #11245995

00:00:20

 
  Build And Test
passed autotools-build-and-test #11245996

00:05:06

passed meson-build-and-test #11245997

00:01:25