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 tangotests.asm3;

extern(C) int printf(char*, ...);

void main()
{
    char* fmt = "Hello D World\n";
    printf(fmt);
    asm
    {
        push fmt;
        call printf;
        pop EAX;
    }
}