Add struct cgit_page to cgit_context

This struct is used when generating http headers, and as such is another
small step towards the goal of the whole cleanup series; to invoke each
page/view function with a function pointer.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/ui-repolist.c b/ui-repolist.c
index cd4e41d..e663585 100644
--- a/ui-repolist.c
+++ b/ui-repolist.c
@@ -51,8 +51,10 @@
 	if (ctx.cfg.enable_index_links)
 		columns++;
 
-	cgit_print_docstart(ctx.cfg.root_title, item);
-	cgit_print_pageheader(ctx.cfg.root_title, 0);
+	ctx.page.title = ctx.cfg.root_title;
+	cgit_print_http_headers(&ctx);
+	cgit_print_docstart(&ctx);
+	cgit_print_pageheader(&ctx);
 
 	html("<table summary='repository list' class='list nowrap'>");
 	if (ctx.cfg.index_header) {