SSL: fixed compatibility with OpenSSL 1.1.0.

SSL_CTRL_CLEAR_OPTIONS is no longer defined, but SSL_clear_options()
is still available.

Change-Id: Iecca3e9444146d979632053207bcec9adb50c815
Signed-off-by: Piotr Sikora <piotrsikora@google.com>

src/http/ngx_http_request.c

diff --git a/src/http/ngx_http_request.c b/src/http/ngx_http_request.c
index 808d1c1..1b00efd 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -912,8 +912,7 @@
 
         SSL_set_verify_depth(ssl_conn, SSL_CTX_get_verify_depth(sscf->ssl.ctx));
 
-#ifdef SSL_CTRL_CLEAR_OPTIONS
-        /* only in 0.9.8m+ */
+#if OPENSSL_VERSION_NUMBER >= 0x009080dfL
         SSL_clear_options(ssl_conn, SSL_get_options(ssl_conn) &
                                     ~SSL_CTX_get_options(sscf->ssl.ctx));
 #endif