We often need the same native texture objects for new textures. This commit
try to avoid destroying and creation of this textures by pooling them.
This should be a big performance gain for some efb2ram games as they may
overwrites partially a cached texture (which would be deleted) and afterwards
try to read it.
Creating/destroying sounds like an easy task, but it isn't. eg the nvidia ogl
driver synchonize their threads do avoid use-after-free issues.
degasus
6cece6b486