- Improved rsyserr() to prefix RSYNC_NAME (as the TODO requested),

- Improved rsyserr() to prefix RSYNC_NAME (as the TODO requested),
  to construct the string in a better manner, and to have a buffer
  big enough to hold a full MAXPATHLEN filename plus some error
  text.
- Fixed some comments referring to vsprintf() returning -1 -- our
  configuration process now ensures that we replace such a function
  with our own lib version.