This update for gzdoom fixes the following issues:

Update to release 4.6. 

* Widescreen graphics for Heretic and Hexen
* Sprite shadows like in the Build engine. Both in software and hardware renderer.
* 16 bit channel PNG files can be read.
* DEHEXTRA working properly now.
* Various enhancements and fixes for ZScript.
* For all of Doom's fullscreen images, there's now widescreen versions provided.
* A simplified options menu is now available for quick setup of the important settings.
* New keybindings presets. Users can now choose between the classic layout and a WASD-based one.
* Turn off LTO, to fix segmentation fault. (boo#1142267)