Per discussion in [0], here is a patch set that allows pfree() to accept
a NULL argument, like free() does.
Also, a patch that removes the now-unnecessary null pointer checks
before calling pfree(). And a few patches that do the same for some
other functions that I found around. (The one with FreeDir() is perhaps
a bit arguable, since FreeDir() wraps closedir() which does *not* accept
NULL arguments. Also, neither FreeFile() nor the underlying fclose()
accept NULL.)
[0]: https://www.postgresql.org/message-id/1074830.1655442689@sss.pgh.pa.us