deps: float 26d7fce1 from openssl

The fix for CVE-2018-0734, floated in 213c7d2d, failed to include a
constant-time calculation for one of the variables. This introduces
a fix for that.

Upstream: https://github.com/openssl/openssl/commit/26d7fce1



Original commit message:
  Add a constant time flag to one of the bignums to avoid a timing leak.

Reviewed-by: Tim Hudson <tjh@openssl.org>
  (Merged from https://github.com/openssl/openssl/pull/7549)

  (cherry picked from commit 00496b6423605391864fbbd1693f23631a1c5239)

PR-URL: https://github.com/nodejs/node/pull/24353
Refs: https://github.com/openssl/openssl/pull/7549


Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>