pthread subsystem on BSD/OS because pthread_self() fails to initialize
pthreads implicitly. This patch is contributed by Bert Driehuis
<bert_driehuis@nl.compuware.com>.
1. Ports to older revisions of some Unix variants, e.g., BSD/OS 1.1,
OSF1 V2.0, etc., contributed by Brian Ostrom <briano@netscape.com>.
2. QNX port, also contributed by Brian Ostrom.
3. New macro USE_MACH_DYLD to represent the dynamic library loading
API of NEXTSTEP and Rhapsody.
4. On platforms whose socket address has the sa_len field, make a
copy of the PRNetAddr argument for PR_Bind, PR_Connect, and PR_SendTo
and set its sa_len before passing it to the system calls. This
fix is suggested by Bert Driehuis <driehuis@playbeing.org>.
5. Removed the unused field _lockf64 of struct _MD_IOVector. Not
every Unix platform has lockf, and the POSIX file locking API
uses fcntl.
