SSL: optimized updates of SSL context.

Previously, unnecessary updates of SSL context could have happened when
selected server didn't change, e.g. when it was the default server.

Change-Id: Idd36f5c37011bb25164aa27b6ed7796007f022a5
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 1b00efd..364067f 100644
--- a/src/http/ngx_http_request.c
+++ b/src/http/ngx_http_request.c
@@ -899,7 +899,7 @@
 
     c->ssl->buffer_size = sscf->buffer_size;
 
-    if (sscf->ssl.ctx) {
+    if (sscf->ssl.ctx && sscf->ssl.ctx != SSL_get_SSL_CTX(ssl_conn)) {
         SSL_set_SSL_CTX(ssl_conn, sscf->ssl.ctx);
 
         /*