Change OPEN_BLOCKING|OPEN_UNBUFFERED to OPEN_BLOCKING.
Change OPEN_BLOCKING|OPEN_UNBUFFERED to OPEN_BLOCKING.

Georg reports that Mozilla is doing so internally anyway. We were never
really getting OPEN_UNBUFFERED.

https://trac.torproject.org/projects/tor/ticket/11183#comment:27
https://hg.mozilla.org/mozilla-central/file/fc70d6d9a9b0/netwerk/base/src/nsSocketTransport2.cpp#l1952

All OPEN_UNBUFFERED is supposed to do is guarantee that the stream
support ReadSegments/WriteSegments/WriteFrom. It doesn't hurt if it
does, but we don't use them.

https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsITransport#openInputStream%28%29
https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XPCOM/Reference/Interface/nsITransport#openOutputStream%28%29

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