Allow user to pass integer into embind exported function taking pointer

Because pointers are just int or long in memory64. User would normally expect result from ```malloc``` being passed straight in without a problem, but turns out, currently, they will need to change to make their function taking an ```int``` and ```reinterpret_cast``` it to a pointer to be able to use it. An embind signature mismatch error will pop up if that wasn't done.