Re: [PATCH v10] GSSAPI encryption support

Hello friends,

Here is another version of GSSAPI encryption support, both on this email
and on my github:
https://github.com/frozencemetery/postgres/tree/feature/gssencrypt10

This version is intended to address Michael's review:

- Fixed Windows build.  Thanks to Michael for patches.

- Fixed buffering of large replies on the serverside.  This should fix
  the traceback that was being seen.  The issue had to do with the
  difference between the server and client calling conventions for the
  _read and _write functions.

- gss_enc_require renamed to gss_require_encrypt.  Slightly longer, but
  half the stomach churn.

- Move gss_encrypt out of the GUCs and into connection-specific logic.
  Thanks to Tom Lane for pointing me in the right direction here.

- Replace writev() with two calls to _raw_write().  I'm not attached to
  this design; if someone has a preference for allocating a buffer and
  making a single write from that, I could be persuaded.  I don't know
  what the performance tradeoffs are.

- Typo fixes.  I need to figure out spellchecking in my editor.

- More use of <acronym>.

- Change _should_crypto() functions to return bool.  Also rename them to
  be the _should_encrypt functions.

- Error message cleanup.

Thanks!