multimedia/zoneminder: fix build on armv7 (again)

After pkubaj@ fixed armv7 support in ports commit 5094662, the fix was
upstreamed. Unfortunately upstream made a mistake in processing the
patch, leading to broken code on armv7. This was subsequently fixed in
the linked commit, but has not made its way into the ports tree yet.

Fix the build once again by importing the patch from the commit above.

See also: https://cgit.freebsd.org/ports/commit/?id=50946628c31aff06f6ff06504d5164466d34428c
See also: https://github.com/ZoneMinder/zoneminder/commit/78a10b6095b3759d341a1a336ac2b73a880871b4

PR: 264550
Approved by: bsd@abinet.ru (maintainer)