Fix SRP ciphersuites.

Add patch missed from backport of SRP ciphersuite fix.
PR#3490
Reviewed-by: Kurt Roeckx <kurt@openssl.org>
Further improve/fix ec_GFp_simple_points_make_affine (ecp_smpl.c) and
group_order_tests (ectest.c).  Also fix the EC_POINTs_mul documentation (ec.h).

Reviewed-by: emilia@openssl.org
Fixed out-of-bounds read errors in ssl3_get_key_exchange.

PR#3450

Conflicts:
	ssl/s3_clnt.c

Reviewed-by: Emilia Käsper <emilia@openssl.org>