Merge branch 'fix-mygui-log' into 'master'

Fix MyGUI log

Closes #5900

See merge request OpenMW/openmw!660

apps/openmw/mwgui/windowmanagerimp.cpp

@@ -189,7 +189,7 @@ namespace MWGui
     {
         float uiScale = Settings::Manager::getFloat("scaling factor", "GUI");
         mGuiPlatform = new osgMyGUI::Platform(viewer, guiRoot, resourceSystem->getImageManager(), uiScale);
-        mGuiPlatform->initialise(resourcePath, logpath);
+        mGuiPlatform->initialise(resourcePath, (boost::filesystem::path(logpath) / "MyGUI.log").generic_string());
 
         mGui = new MyGUI::Gui;
         mGui->initialise("");

components/myguiplatform/myguiloglistener.cpp

@@ -2,11 +2,15 @@
 
 #include <iomanip>
 
+#include <components/debug/debuglog.hpp>
+
 namespace osgMyGUI
 {
     void CustomLogListener::open()
     {
         mStream.open(boost::filesystem::path(mFileName), std::ios_base::out);
+        if (!mStream.is_open())
+            Log(Debug::Error) << "Unable to create MyGUI log with path " << mFileName;
     }
 
     void CustomLogListener::close()