- remove USERGROUP_PHASE=pre-install.  Makes binary packages usable on
  systems other than the build host.
- don't install dvd-handler -- DVD support is disabled since version 5.
- install query.sql in client-only package too.
Update to 1.6.2:

Version 1.6.2rc01 [April 18, 2013]
  Added contrib/tools/fixitxt.c, to repair the erroneous iTXt chunk length
    written by libpng-1.6.0 and 1.6.1.
  Disallow storing sRGB information when the sRGB is not supported.

Version 1.6.2rc02 [April 18, 2013]
  Merge pngtest.c with libpng-1.7.0

Version 1.6.2rc03 [April 22, 2013]
  Trivial spelling cleanup.

Version 1.6.2rc04 and 1.6.2rc05 [omitted]

Version 1.6.2rc06 [April 24, 2013]
  Reverted to version 1.6.2rc03.  Recent changes to arm/neon support
    have been ported to libpng-1.7.0beta09 and will reappear in version
    1.6.3beta01.
Updated graphics/png to 1.6.2