x11-toolkits/mygui: update to 3.4.2 release (+)

Switch to latest ogre3d port, MyGUI now can utilize it

Changelog: https://github.com/MyGUI/mygui/releases/tag/MyGUI3.4.1

		https://github.com/MyGUI/mygui/releases/tag/MyGUI3.4.2

Approved by: amdmi3 (maintainer)