test Content-Type via hash:

*) ngx_http_test_content_type()
*) ngx_http_types_slot()
*) ngx_http_merge_types()
diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index be22db6..9a62239 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -244,6 +244,8 @@
     size_t                            content_type_len;
     ngx_str_t                         content_type;
     ngx_str_t                         charset;
+    u_char                           *content_type_lowcase;
+    ngx_uint_t                        content_type_hash;
 
     ngx_array_t                       cache_control;