send "100 Continue" for HTTP/1.1 only

src/http/ngx_http_core_module.c

diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 4f2b325..8f25f1a 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -862,7 +862,7 @@
         return NGX_OK;
     }
 
-    if (r->headers_in.expect) {
+    if (r->headers_in.expect && r->http_version < NGX_HTTP_VERSION_11) {
         expect = ngx_http_core_send_continue(r);
 
         if (expect != NGX_OK) {