Missing implementations of 64 bit MachOps in 32 bit backend

In #23537 and T22871, we've started noticing failures due to missing implementations of 64 bit operations in the 32 bit backend. These operations were supposed to be translated into CallishMachOps, however it seems some still slip through the cracks and end up as normal MachOps. We could try to patch up those cracks, but perhaps it is time now to actually properly implement all 64 bit operations. Then we could stop relying on the 64-bit int/word CallishMachOps and stop worrying.