[openssl/openssl] 42ca6c: Deprecate SPT threading support on NonStop.

[Randall S. Becker]

  Branch: refs/heads/openssl-3.2
  Home:   https://github.com/openssl/openssl
  Commit: 42ca6c042b5fd40eb0a2729aea0e83086b0056bf
      https://github.com/openssl/openssl/commit/42ca6c042b5fd40eb0a2729aea0e83086b0056bf
  Author: Randall S. Becker <randall.becker at nexbridge.ca>
  Date:   2023-12-12 (Tue, 12 Dec 2023)

  Changed paths:
    M Configurations/50-nonstop.conf
    M NOTES-NONSTOP.md
    M crypto/bio/bio_sock.c

  Log Message:
  -----------
  Deprecate SPT threading support on NonStop.

This fix removes explicit support for the SPT threading model in configurations.
This also reverts commit f63e1b48ac893dd6110452e70ed08f191547cd89 that were
required for SPT but broke other models.

Fixes: #22798

Signed-off-by: Randall S. Becker <randall.becker at nexbridge.ca>

Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Neil Horman <nhorman at openssl.org>
Reviewed-by: Hugo Landau <hlandau at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22807)

(cherry picked from commit 5cd17920167a8b4f7a81722a1ed3b514115702de)