0.pre7.103:
rewrote LOOKUP-LOGIN-NAME to use getpwuid() instead of
parsing "/etc/passwd" and then trying to speed up that
fundamentally slow process by maintaining a
fundamentally bogus cache of previous lookup results...
...deleted *UID-HASH-TABLE*
...deleted GET-GROUP-OR-USER-NAME
...deleted GET-GROUP-OR-USER-NAME-AUX
...defined uid_username() in wrap.c to encapsulate the
C-level struct dereferencing
...factored the C-to-Lisp conversion logic out of POSIX-GETCWD,
anticipating reusing it in LOOKUP-LOGIN-NAME
...rewrote LOOKUP-LOGIN-NAME to call uid_username(), and
renamed it to UID-USERNAME