Check for AMDGPU_CREATE_PIXMAP_SCANOUT in amdgpu_glamor_create_pixmap
requested to merge daenzer/xf86-video-amdgpu:amdgpu_glamor_create_pixmap-AMDGPU_CREATE_PIXMAP_SCANOUT into master
We must not call glamor_create_pixmap or fbCreatePixmap when it's set.
Closes: #21 (closed)