x11/kitty: fix build on 32 bit platforms

Structure Kevent_t of golang.org/x/sys/unix has different types depending
on word size on FreeBSD, causing trouble. Work around the problem with
a conditional patch.

Approved by: portmgr (build fix blanket)
MFH: 2026Q3
See also: https://github.com/sgtdi/fswatcher/issues/24