BUILD: auth: include missing list.h

list_for_each_entry() requires list.h but used to inherit it by accident
through global.h and mworker-t.h. Let's explicitly add it.

src/auth.c

@@ -29,6 +29,7 @@
 #include <haproxy/auth-t.h>
 #include <haproxy/errors.h>
 #include <haproxy/global.h>
+#include <haproxy/list.h>
 #include <haproxy/pattern-t.h>
 #include <haproxy/sample-t.h>
 #include <haproxy/thread.h>