glamor: use glEGLImageTargetTexture2DOES during copy to update image texture

Texture sampling buffers may not be accepted in the same format as an image's generated renderbuffer, so glamor should explicitly refresh the texture's base image during the copy from the GL client to its X window.

This fix specifically addresses the most common PresentPixmap operations, and does not attempt to support other DRI3 pixmap drawing operations.

Fixes: mesa/mesa#6220 (closed)

Signed-off-by: Kyle Russell bkylerussell@gmail.com