OpenBSD doesn't have posix_fallocate

Index: uitoolkit/wayland/ui_display.c
--- uitoolkit/wayland/ui_display.c.orig
+++ uitoolkit/wayland/ui_display.c
@@ -94,7 +94,7 @@ static int create_anonymous_file(off_t size) {
     return -1;
   }
 
-  if (posix_fallocate(fd, 0, size) != 0) {
+  if (ftruncate(fd, size) != 0) {
     close(fd);
     return -1;
   }
