Zhigang Gong authored Jan 18, 2012 and Emma Anholt committed Dec 18, 2013

This is the first patch to implement a fbo/tex pool mechanism which
is like the sna's BO cache list. We firstly need to decopule the
fbo/tex from each pixmap. The new glamor_pixmap_fbo data
structure is for that purpose. It's somehow independent to each
pixmap and can be reused latter by other pixmaps once it's detached
from the current pixmap.

And this commit also slightly change the way to create a
memory pixmap. We will not create a pixmap private data structure
by default, instead we will crete that structure when a memory
pixmap is attaching a fbo to it.

Signed-off-by: Zhigang Gong <zhigang.gong@linux.intel.com>