plugins: add support for EGLImage memory inputs
@gb
Submitted by Gwenole Beauchesne Link to original bug (#743850)
Description
Add support for video/x-raw(memory:EGLImage) inputs from vaapipostproc primarily, and optionally for vaapiencode_* elements too. The purpose is to avoid a roundtrip to CPU backed memory and thus directly supporting EGLImage generated from upstream elements, which could be wrapped off a 2D texture or EGLSurface.