Fixed memory leak if BUF_MEM_grow fails

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Kurt Roeckx <kurt@openssl.org>
(cherry picked from commit bb1ddd3d9a0d01656b90693a214b911995a5fe8c)
Fix memory leak in s2_srvr.c if BUF_MEM_grow fails

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Kurt Roeckx <kurt@openssl.org>
(cherry picked from commit d04a1e0b5beb3329cdf8c4ec35b9113cbc41d2f2)