Blender Git Loki

Fix T50094: Crash when viewport rendering point density texture

The idea is simple: cache PD resolution from cache_point_density() RNA
function because that one is supposed to be called while database is
locked for original synchronization.

Ideally we would also pass array size to the sampling function, but
it turned out to be quite problematic because API only accepts int type
and passing size_t might cause some weird behavior.