Fixed memory leak in the event of a failure of BUF_MEM_grow

Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 41bf250130)

ssl/s3_srvr.c

@@ -246,6 +246,7 @@ int ssl3_accept(SSL *s)
 					}
 				if (!BUF_MEM_grow(buf,SSL3_RT_MAX_PLAIN_LENGTH))
 					{
+					BUF_MEM_free(buf);
 					ret= -1;
 					goto end;
 					}