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_debug4;

void main()
{
    char c = 'c';
    wchar wc = 'w';
    dchar dc = 'd';

    int* fail;
    *fail = 32;
}