Some errors are impossible to fathom, without the user knowing certain

  Some errors are impossible to fathom, without the user knowing certain
  base numbers.  This patch introduces "(EAP ##): Eap message" for the EAP
  errors, "(OS ##): Message" for modestly numbered os errors (under 100000)
  and hex "(OS 0x########): Message" for huge errors, which generally have
  bit-flag meanings and are usually represented in hex.

  This should make recognizing user bugreports a little less difficult.
  Would have done the same for other ranges, but they don't have (as) obvious
  numeric meanings on their own.

  Finally, we free up a buffer copy and give apr_strerror our string buffer
  to directly populate the message text.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@97191 13f79535-47bb-0310-9956-ffa450edef68