Previously when PointLocatorUniformGrid.h was compiled by the CUDA
compiler, the compiler would crash. Apparently during the ptxas
part of the compiler goes into a crazy recursion and runs out of
stack space. This appears to be a long-standing bug in CUDA
(been there for multiple releases) without a clear reason why it
sometimes rears its ugly head. (See for example
https://devtalk.nvidia.com/default/topic/1028825/cuda-programming-and-performance/-ptxas-died-with-status-0xc00000fd-stack_overflow-/)
The problem appears to be when having a doubly or triply nested
loop over a box of values to check in the uniform array. This
appears to fix the problem by converting that to a single for
loop with some index magic to convert that to 3D indices.
This means that we not only setup the runtime device tracker
to force the intended device, it also means making sure
the default device is the error device.
Modify PointLocatorUniform::Build to return an ExecutionObjec, Locator.
The Locator can the be passed to Worklets for finding neareast neighbor
point by calling the FindNeareastPoint method.
