Get binaries closer to running without an o/s

blinkenlights now does a pretty good job emulating what happens when
binaries boot from BIOS into long mode. So it's been much easier to
debug the bare metal process and wrinkle out many issues.

libc/log/asan.c

@@ -140,6 +140,7 @@ static const char *__asan_describe_access_poison(int c) {
     case kAsanUnscoped:
       return "unscoped";
     default:
+      DebugBreak();
       return "poisoned";
   }
 }