These patches implement an LDS memory allocator for OpenMP on AMD.

1. 230216-basic-allocator.patch

Separate the allocator from NVPTX so the code can be shared.

2. 230216-amd-low-lat.patch

Allocate the memory, adjust the default address space, and hook up the 
allocator.

They will need to be integrated with the rest of the memory management 
patch-stack when I repost that for mainline.

Andrew