Fix env_universal_common.cpp filesize comparisons.

* if (result == ULLONG_MAX) is always false, likely a typo as
  result is unsigned long, and the comment says ULONG_MAX.

* use off_t instead of size_t for file size where it can mismatch
  st_size's type in stat.h

src/env_universal_common.cpp

@@ -1551,7 +1551,7 @@ class universal_notifier_named_pipe_t : public universal_notifier_t
         // Now return the smaller of the two values
         // If we get ULONG_MAX, it means there's no more need to poll; in that case return 0
         unsigned long result = mini(readback_delay, polling_delay);
-        if (result == ULLONG_MAX)
+        if (result == ULONG_MAX)
         {
             result = 0;
         }