radv: Support VK_EXT_inline_uniform_block.

radv: Support VK_EXT_inline_uniform_block.

Basically just reserve the memory in the descriptor sets.

On the shader side we construct a buffer descriptor, since
AFAIU VGPR indexing on 32-bit pointers in LLVM is still broken.

This fully supports update after bind and variable descriptor set
sizes. However, the limits are somewhat arbitrary and are mostly
about finding a reasonable division of a 2 GiB max memory size over
the set.

v2: - rebased on top of master (Samuel)
    - remove the loading resources rework (Samuel)
    - only load UBO descriptors if it's a pointer (Samuel)
    - use LLVMBuildPtrToInt to avoid IR failures (Samuel)

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> (v2)