Mostly rewrite debug info generation in terms of llvm/Analysis/DebugInfo.h. Add getCompilationModule to Dsymbol and fix template compile unit decision code. Runtime compiles with -g again.

module tuple1;

template Tuple(T...) {
    alias T Tuple;
}

struct S
{
    int i;
    long l;
}

void main()
{
    S s = S(Tuple!(1,2L));
    assert(s.i == 1);
    assert(s.l == 2);
}