lib/, src/: Make the use of MAYBE_UNUSED macro consistent

There is an inconsistent use of the MAYBE_UNUSED macro. Sometimes the
`int unused(x)` form is used form and others the `unused int x`. We'd
like to use the second form always.

Related-To: https://github.com/shadow-maint/shadow/issues/918

Suggested-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Pablo Saavedra <psaavedra@igalia.com>

lib/logind.c

@@ -36,7 +36,7 @@ done:
     return ret;
 }
 
-unsigned long active_sessions_count(const char *name, unsigned long MAYBE_UNUSED(limit))
+unsigned long active_sessions_count(const char *name, MAYBE_UNUSED unsigned long limit)
 {
     struct passwd *pw;
     unsigned long count = 0;

src/grpconv.c

@@ -262,7 +262,7 @@ int main (int argc, char **argv)
 	return 0;
 }
 #else				/* !SHADOWGRP */
-int main (int MAYBE_UNUSED(argc), char **argv)
+int main (MAYBE_UNUSED int argc, char **argv)
 {
 	fprintf (stderr,
 		 "%s: not configured for shadow group support.\n", argv[0]);

src/grpunconv.c

@@ -224,7 +224,7 @@ int main (int argc, char **argv)
 	return 0;
 }
 #else				/* !SHADOWGRP */
-int main (int MAYBE_UNUSED(argc), char **argv)
+int main (MAYBE_UNUSED int argc, char **argv)
 {
 	fprintf (stderr,
 		 "%s: not configured for shadow group support.\n", argv[0]);

src/su.c

@@ -111,7 +111,7 @@ static void execve_shell (const char *shellname,
                           char *args[],
                           char *const envp[]);
 #ifdef USE_PAM
-static void kill_child (int MAYBE_UNUSED(s));
+static void kill_child (MAYBE_UNUSED int s);
 static void prepare_pam_close_session (void);
 #else				/* !USE_PAM */
 static void die (int);
@@ -165,7 +165,7 @@ static bool iswheel (const char *username)
 	return is_on_list (grp->gr_mem, username);
 }
 #else				/* USE_PAM */
-static void kill_child (int MAYBE_UNUSED(s))
+static void kill_child (MAYBE_UNUSED int s)
 {
 	if (0 != pid_child) {
 		(void) kill (-pid_child, SIGKILL);