Various cleanups: threads, STA_NANO

[Hal Murray]

> The C code has no #ifdefs for HAVE_PTHREAD or HAVE_PTHREAD_H, so we're only
> talking about cleaning up some waf python code, correct?

Yes, or eliminating it.

Simplifying "little" things like this often allows simplification in some 
other area.

--------

> libthr is a FreeBSD thing...

Thanks.

On a FreeBSD system, I just commented out these two lines:
#    ctx.check_cc(lib="thr", mandatory=False,
#                 comment="thr library, required by some operating systems.")
And it still builds and ends up using libthr.

The man page says:
     POSIX Threads Library (libpthread, -lpthread)
I assume there is magic in there to translate -lpthhead to -lthr, but maybe 
it's just getting it from libcrypto.

But this is all tangled up with -pthread vs -lpthread and that discussion 
suggests out of date documentation, so who knows what is going on.



-- 
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