tdf#44497 run LicenseDialog with SolarMutex locked

Before commit 3840aede releasing
an unlocked SolarMutex was simply ignored, but now it aborts.

So run the LicenseDialog GUI code holding the SolarMutex, as
required.

Change-Id: Id9f5f6146cdfe2b21b68a2cdffc9dd4a527b551c
Reviewed-on: https://gerrit.libreoffice.org/42951Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

desktop/source/deployment/gui/dp_gui_extensioncmdqueue.cxx

@@ -392,6 +392,7 @@ void ProgressCmdEnv::handle( uno::Reference< task::XInteractionRequest > const &
     }
     else if (request >>= licExc)
     {
+        SolarMutexGuard guard;
         uno::Reference< ui::dialogs::XExecutableDialog > xDialog(
             deployment::ui::LicenseDialog::create(
             m_xContext, VCLUnoHelper::GetInterface( m_pDialogHelper? m_pDialogHelper->getWindow() : nullptr ),