[sledge] Use Typ.prim_bit_size_of instead of Integer {bits}
[sledge] Use Typ.prim_bit_size_of instead of Integer {bits}

Summary:
This is significant for operations involving the NULL pointer, which
is an integer of pointer type.

Reviewed By: mbouaziz

Differential Revision: D14075516

fbshipit-source-id: b727cb4c8

jvillard/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer