We should only use size_t when referring to sizes of bits of CPU memory.
Anything on the GPU or just a regular array length should be a type that
has the same size on both 32 and 64-bit architectures.  For state
objects, we use a uint32_t because we'll never allocate a piece of
driver-internal GPU state larger than 2GB (more like 16KB).

Reviewed-by: Juan A. Suarez Romero <jasuarez@igalia.com>