So happy to find this thread!
I tried the last shader which was pasted but didnt have any luck getting it to work on my devices.
It crashes retroarch on my HTC DNA when applied. On nvidia shield (portable) nothing happens.
Other shaders do seem to be working. Interestingly the side by side shader (from http://libretro.com/forums/showthread.php?t=2628&page=2 ) works on the shield but crashes my HTC DNA.
Is there a required version of gl es? What hardware did you get it working on?