- fix outrun of buffer when Host: header contained :port in ipv4 requests

- fix outrun of buffer when Host: header contained :port in ipv4 requests
  src/main/http_vhost.c@fix_hostname(), bug introduced in r1.6 (4 years, 9 months ago)
  thx patrys for helping debugging this.
  as a result time to time 400 responses were given with "Client sent malformed
  Host header" in error log, depending what was in memory left from previous
  request.

Changed files:
    apache1-ipv6-PLD.patch -> 1.15