apps/speed.c: add 'rand' algo to enable DRBG performance measurements.

Signed-off-by: Patrick Steuer <patrick.steuer@de.ibm.com>

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4481)