[PATCH] open_memstream() and open_wmemstream()

I've written an implementation of open_memstream() and open_wmemstream() along 
with a set of regression tests.  I'm pretty sure open_memstream() is correct, 
and I believe open_wmemstream() is correct for expected usage.  The latter 
might even do the right thing if you split a multi-byte character across 
multiple writes.  One question I have is if my choice to discard any pending 
multi-byte state in the stream anytime a seek changes the effective position 
in the output stream.  I think this is correct as stdio will flush any pending 
data before doing a seek, so if there is a partially parsed character we 
aren't going to get the rest of it.

http://www.FreeBSD.org/~jhb/patches/open_memstream.patch

-- 
John Baldwin