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 scope3;
extern(C) int printf(char*, ...);
void main()
{
    int i;
    while (i < 10) {
        scope(success) i++;
    }
    printf("%d\n", i);
}