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 scope2;
extern(C) int printf(char*, ...);
void main()
{
    scope(exit) printf("exit\n");
    scope(failure) printf("failure\n");
    scope(success) printf("success\n");
}