Fix VarDecls for tuples. Closes #99. I've implemented it this way since it doesn't require any changes in the frontend. However, I think having TypeTuple expressed as LLVM struct types would make much more sense and open the door to tuple lvalues.

module scope2;
extern(C) int printf(char*, ...);
void main()
{
    scope(exit) printf("exit\n");
    scope(failure) printf("failure\n");
    scope(success) printf("success\n");
}