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 bug45;

void foo() {
    int bar;
    scope(exit) { bar++; }
    if (bar) return;
}

void main() {
    foo();
}