lib/logind.c: active_sessions_count(): Fix build error 'parameter name omitted'

Add the omitted parameter name.

Closes: <https://github.com/shadow-maint/shadow/issues/918>
Link: <https://github.com/shadow-maint/shadow/pull/919>
Signed-off-by: Pablo Saavedra <psaavedra@igalia.com>
Cherry-picked-from: da84d0ede7 ("Fix Build error 'parameter name omitted' in logind")
Cc: Michael Vetter <jubalh@iodoru.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/logind.c

@@ -35,7 +35,7 @@ done:
     return ret;
 }
 
-unsigned long active_sessions_count(const char *name, unsigned long unused)
+unsigned long active_sessions_count(const char *name, unsigned long unused(limit))
 {
     struct passwd *pw;
     unsigned long count = 0;