Add operator= on IntType

Before C++11 types with custom operator= were not allowed in unions.
I cannot replicate this error by passing -std=c++03 to gcc.
I know if I add a constructor, some of the bots will be unhappy.
Testing for operator= to see if this passes through.  I know way
back when, I removed operator= and added set() method because
someone complained.  But that was ten years ago I think.
1 file changed