clover: Use cl_ulong in the maximum allocation size calculation to avoid overflow.

src/gallium/state_trackers/clover/api/memory.cpp

@@ -37,7 +37,7 @@ clCreateBuffer(cl_context d_ctx, cl_mem_flags flags, size_t size,
       throw error(CL_INVALID_HOST_PTR);
 
    if (!size ||
-       size > fold(maximum(), 0u,
+       size > fold(maximum(), cl_ulong(0),
                    map(std::mem_fn(&device::max_mem_alloc_size), ctx.devs())
           ))
       throw error(CL_INVALID_BUFFER_SIZE);