Change login failure message to show the login type (admin or user)

public/login.php

@@ -73,7 +73,7 @@ if ($_SERVER['REQUEST_METHOD'] == "POST") {
         header("Location: main.php");
         exit(0);
     } else { # $h->login failed
-        error_log("PostfixAdmin login failed (username: $fUsername, ip_address: {$_SERVER['REMOTE_ADDR']})");
+        error_log("PostfixAdmin admin login failed (username: $fUsername, ip_address: {$_SERVER['REMOTE_ADDR']})");
         flash_error($PALANG['pLogin_failed']);
     }
 }

public/users/login.php

@@ -53,7 +53,7 @@ if ($_SERVER['REQUEST_METHOD'] == "POST") {
         header("Location: main.php");
         exit;
     } else {
-        error_log("PostfixAdmin login failed (username: $fUsername)");
+        error_log("PostfixAdmin user login failed (username: $fUsername)");
         flash_error($PALANG['pLogin_failed']);
     }
 }