(access, unlink) [WINDOWSNT]: Macros undefined.

(access, unlink) [WINDOWSNT]: Macros undefined.
(fork, syswait, DISABLE_DIRECT_ACCESS) [WINDOWSNT]: Macros defined.
[WINDOWSNT]: Include locking.h.
(main): Update usage message.  Use IS_DIRECTORY_SEP.
(main) [DISABLE_DIRECT_ACCESS]: Don't check access if defined.
(main) [WINDOWSNT]: Invoke locking instead of flock.
(main) [MAIL_USE_SYSTEM_LOCK && WINDOWSNT]: Emulate ftruncate.
(main) [MAIL_USE_POP]: Pass password to popmail if used.
Include winsock.h; don't include unix inet headers.
(popmail): Add password argument and pass it to pop_open.
Open output file in binary mode.