libos: Support comments in config files

base/etc/loginui.conf

@@ -1,2 +1,5 @@
+# Configuration file for loginui.
+# If this parameter is set to "true", loginui automatically spawns a UI session as the below user instead of prompting for a username and password.
 Autologin=true
+# The user to create a session for if "Autologin" is set to true (see above). If the username is invalid, loginui will behave as if "Autologin" was set to false.
 AutologinUser=selene

libos/src/Config.cpp

@@ -28,6 +28,9 @@ namespace os
             line.trim("\n");
             if (line.is_empty()) continue;
 
+            // Skip comment lines.
+            if (line[0] == '#') continue;
+
             auto parts = TRY(line.split_once('='));
             if (parts.size() < 2 || parts[0].is_empty() || parts[1].is_empty()) return err(EINVAL);