With this new approach, descriptor pools are decoupled from the
command list they are used with. Instead, the DXVK context takes
ownership of a single descriptor pool until it runs out of memory.
This reduces the amount of memory wasted for under-utilized pools
and should this reduce an application's memory footprint.
This should more closely reflect what applications actually use.
The basic idea here is that it is better for apps to run out of
descriptors before running out of sets and thus reduce the
overall memory footprint of the application.
Fixes a few bottlenecks that were encountered in the Cascading Shadow
Maps demo from the Microsoft SDK. Performance is now slightly better
than wined3d with CSMT, MESA_NO_ERROR and mesa_glthread enabled.
