We should audit the rest of keyman32/keyman64 for use of improper casts of pointers to int.

It is unlikely to cause a problem presently because we currently have a base address fixed in the keyman64.dll below 2GB (which itself is not recommended...) so we should probably put this in as a maintenance issue. It could arise if Windows needs to relocate the dll I guess.

Originally posted by @mcdurdin in #3076