[platforms/x11/standalone] Pass kxkbconfig to Xkb prior to reconfigure

Summary:
This ensures that KWin gets the same keyboard layout config as is
configured in the session and not a default config.

BUG: 402764
FIXED-IN: 5.14.5

Test Plan:
Xephyr to verify the config is applied, otherwise completely
untested. I don't have an X session.

Reviewers: #kwin

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D17967

plugins/platforms/x11/standalone/x11_platform.cpp

@@ -146,6 +146,7 @@ void X11StandalonePlatform::createPlatformCursor(QObject *parent)
         m_xinputIntegration->setCursor(c);
         // we know we have xkb already
         auto xkb = input()->keyboard()->xkb();
+        xkb->setConfig(kwinApp()->kxkbConfig());
         xkb->reconfigure();
     }
 #endif