:pre not working on macOS, missing /var/tmp/vi.recover

`:preserve` does not seem to work with macOS/homebrew v7.4.26 using the default `/var/tmp/vi.recover` location.

Low priority.

Works normally on GNU/Linux (compiled).

Simple missing directory:

$ ovi -r
Error: recdir: /var/tmp/vi.recover: No such file or directory

~
:pre
Preservation of this file not possible

:set recdir?
recdir="/var/tmp/vi.recover"

$ ls -la /var/tmp/vi*
ls: /var/tmp/vi*: No such file or directory

`/var/tmp` **does** exist so maybe add `mkdir -p /var/tmp/vi.recover` to the build process somehow?
Appears to work like I'd expect once I do that manually.

`mkdir -p /home/kajukenbo/vi.recover` and `set recdir="/home/kajukenbo/vi.recover"` also seems to work.

Thanks as always for keeping `vi` alive.