The import of openssl to address the FreeBSD-SA-15:10.openssl security

The import of openssl to address the FreeBSD-SA-15:10.openssl security
advisory includes a change which rejects handshakes with DH parameters
below 768 bits.  sendmail releases prior to 8.15.2 (not yet released),
defaulted to a 512 bit DH parameter setting for client connections.
This commit chages that default to 1024 bits.  sendmail 8.15.2, when
released well use a default of 2048 bits.

MFC after:	1 day