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 mini.norun_debug5;

void main()
{
    int i = 32;
    real r = 3.1415;
    real* p = &r;
    func(i,r,p);
}

void func(int i, real r, real* p)
{
    int* fail;
    *fail = 666;
}