plugins/screencast: don't crash if eglQueryDmaBufModifiersEXT isn't available
Checking for nullptr doesn't work with epoxy. As an alternative, we could check for the extension being advertised in the screen cast code and/or do the same manual querying for functions, but imo this is simpler
As a side note, I thought we needed to use explicit modifiers for NVidia. How does this all work if they don't expose it through egl? Or is epoxy just incapable of getting the correct function pointers...
Edited by Xaver Hugl