Option to disable padding extension.

Add TLS padding extension to SSL_OP_ALL so it is used with other
"bugs" options and can be turned off.

This replaces SSL_OP_SSLREF2_REUSE_CERT_TYPE_BUG which is an ancient
option referring to SSLv2 and SSLREF.

PR#3336
(cherry picked from commit 758415b2259fa45d3fe17d8e53ae1341b7b6e482)

Conflicts:

	ssl/t1_lib.c