The warning fixes are:
- Only define issetugid if it's missing.
- Explicitly ignore the return value of writev.
- Explicitly cast the retval of readlink() to int.
The 64-bit problems are related to just storing a size_t in an int. Not cool! Use a size_t instead.
Fix for bug 6379. Bugfix on 0.2.0.20-rc, which introduced openbsd-malloc.