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
Fix use after free bug.

Reviewed-by: Stephen Henson <steve@openssl.org>
Reviewed-by: Emilia Käsper <emilia@openssl.org>
(cherry picked from commit 5afa57fb7b17aa51cfba1ffa94e900fc7a5f0e04)
Fixed out-of-bounds read errors in ssl3_get_key_exchange.

PR#3450

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