Kernel may launch GPU kernel with no work

[MrBurmark]

Describe the bug

Sometimes kernel will launch gpu kernels even though they have no work to do.
The gpu implementation of kernel tracks the number of blocks/threads requested and a minimum number of blocks/threads required in each dimension to choose appropriate numbers of blocks and threads. It uses 0 as the default number of blocks/threads and then only chooses not to launch a kernel if all dimensions are still 0 after calculating dimensions.

To Reproduce

Use kernel with a 2d loop over ranges of size 1 and 0 respectively.

Expected behavior

Kernel should not launch a kernel if any dimension in a gpu policy has no work.

Compilers & Libraries (please complete the following information):

• CUDA/HIP version: any

Additional context

Discovered this when I saw segfaults while trying out new "unchecked" policies with 0 length list segments in the test-kernel-nested-loop-segments-HIP test.