Switch to exclusively using global ctx

Drop the context parameter from the following functions (and all static
helpers used by them) and use the global context instead:

* cgit_print_http_headers()
* cgit_print_docstart()
* cgit_print_pageheader()

Remove context parameter from all commands

Drop the context parameter from the following functions (and all static
helpers used by them) and use the global context instead:

* cgit_get_cmd()
* All cgit command functions.
* cgit_clone_info()
* cgit_clone_objects()
* cgit_clone_head()
* cgit_print_plain()
* cgit_show_stats()

In initialization routines, use the global context variable instead of
passing a pointer around locally.

Remove callback data parameter for cache slots

This is no longer needed since the context is always read from the
global context variable.

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>
diff --git a/ui-snapshot.c b/ui-snapshot.c
index 7115ec4..582dc31 100644
--- a/ui-snapshot.c
+++ b/ui-snapshot.c
@@ -121,7 +121,7 @@
 	}
 	ctx.page.mimetype = xstrdup(format->mimetype);
 	ctx.page.filename = xstrdup(filename);
-	cgit_print_http_headers(&ctx);
+	cgit_print_http_headers();
 	format->write_func(hex, prefix);
 	return 0;
 }
@@ -183,9 +183,9 @@
 	va_list ap;
 
 	ctx.page.mimetype = "text/html";
-	cgit_print_http_headers(&ctx);
-	cgit_print_docstart(&ctx);
-	cgit_print_pageheader(&ctx);
+	cgit_print_http_headers();
+	cgit_print_docstart();
+	cgit_print_pageheader();
 	va_start(ap, fmt);
 	cgit_vprint_error(fmt, ap);
 	va_end(ap);