util: Add a wrapper around getuid()

So we can use it from JS in an upcoming commit.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/465

src/shell-util.h

@@ -78,6 +78,8 @@ gboolean shell_util_has_x11_display_extension (MetaDisplay *display,
 
 char *shell_util_get_translated_folder_name (const char *name);
 
+gint shell_util_get_uid (void);
+
 G_END_DECLS
 
 #endif /* __SHELL_UTIL_H__ */