llvmpipe: Use uintptr_t for pointer values

llvmpipe: Use uintptr_t for pointer values

Instead of uint64_t. Fixes potentially writing beyond the end of the
handles pointer array on 32-bit architectures (and copying all 0s
instead of the computed pointer values to the array on big endian
ones).

Corresponding compiler warning:

../src/gallium/drivers/llvmpipe/lp_state_cs.c: In function ‘llvmpipe_set_global_binding’:
../src/gallium/drivers/llvmpipe/lp_state_cs.c:1312:12: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
 1312 |       va = (uint64_t)((char *)lp_res->data + offset);
      |            ^

Fixes: 264663d55d32 "gallivm/llvmpipe: add support for global
                     operations."

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4166>