This change alters the processing of invalid, RSA pre-master secrets so
that bad encryptions are treated like random session keys in constant
time.

(cherry picked from commit adb46dbc6dd7347750df2468c93e8c34bcb93a4b)

Reviewed-by: Rich Salz <rsalz@openssl.org>
RT3067: simplify patch

(Original commit adb46dbc6dd7347750df2468c93e8c34bcb93a4b)

Use the new constant-time methods consistently in s3_srvr.c

Reviewed-by: Kurt Roeckx <kurt@openssl.org>
(cherry picked from commit 455b65dfab0de51c9f67b3c909311770f2b3f801)