[openssl/openssl] bc84a9: Make openVMS seeding less dependent of OpenVMS ver...

[Richard Levitte]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: bc84a93a9923890f00e06087f9b007c6ea819525
      https://github.com/openssl/openssl/commit/bc84a93a9923890f00e06087f9b007c6ea819525
  Author: Richard Levitte <levitte at openssl.org>
  Date:   2022-10-27 (Thu, 27 Oct 2022)

  Changed paths:
    M providers/implementations/rands/seeding/rand_vms.c

  Log Message:
  -----------
  Make openVMS seeding less dependent of OpenVMS version

SYS$GETTIM_PREC is a very new function, only available on OpenVMS v8.4.
OpenSSL binaries built on OpenVMS v8.4 become unusable on older OpenVM
versions, but building for the older CRTL version will make the high
precision time functions unavailable.

Tests have shown that on Alpha and Itanium, the time update granularity
between SYS$GETTIM and SYS$GETTIM_PREC is marginal, so the former plus
a sequence number turns out to be better to guarantee a unique nonce.

Fixes #18727

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18731)

(cherry picked from commit 7056dc9c50baa4af5152c625c4735806d51c67cd)