build: Fix DRI3 on DragonFly and OpenBSD
Commit 96bdc156 added a check for <sys/eventfd.h> to enable DRI3.
DragonFly and OpenBSD however rely on epoll-shim for <sys/eventfd.h>, so that must be added as a dependency for the <sys/eventfd.h> check.
Fixes: commit 96bdc156 - xwayland: Do not enable DRI3 without eventfd
Suggested-by: Jan Beich jbeich@freebsd.org
Signed-off-by: Olivier Fourdan ofourdan@redhat.com
This is UNTESTED!