Log Message:
Upgrade ImageMagick6 from 6.9.7.9 to 6.9.8.5.

Pkgsrc changes:
Adapt to new version, PLIST (2 new files).

Upstream changes:
2017-05-12  6.9.8-5 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.8-5, GIT revision 11575:186b15d:20170512.

2017-05-10  6.9.8-5 John Cupitt <jcupitt@gmail.com>
  * Revise DICOM window and rescale handling (reference
    https://github.com/ImageMagick/ImageMagick/pull/484)

2017-05-08  6.9.8-5 Cristy  <quetzlzacatenango@image...>
  * Fix transient PDF bug (reference
    https://github.com/ImageMagick/ImageMagick/issues/463).
  * Check for EOF conditions for RLE image format.
  * Reset histogram page geometry (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31920).

2017-04-24  6.9.8-4 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.8-4, GIT revision 11521:d7433aa:20170424.

2017-03-26  6.9.8-4 Cristy  <quetzlzacatenango@image...>
  * Minimize buffer copies to improve OpenCL performance.
  * Patch a PCD writer problem, dark pixels (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=3164).
  * Support ICC based PDF's (reference
    https://github.com/ImageMagick/ImageMagick/issues/417).

2017-03-24  6.9.8-3 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.8-3, GIT revision 11444:3f523e5:20170324.

2017-03-20  6.9.8-3 Cristy  <quetzlzacatenango@image...>
  * MagickWand-config, use --cflags, not --clags (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31602).
  * Respect -loop option for animate -window (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31619).

2017-03-18  6.9.8-2 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.8-2, GIT revision 11436:a912791:20170318.

2017-03-14  6.9.8-2 Cristy  <quetzlzacatenango@image...>
  * Support namespaces for the security policy.

2017-03-11  6.9.8-1 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.8-1.

2017-03-03  6.9.8-0 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.8-0, GIT revision 11408:da91a7c:20170311.

2017-03-06  6.9.8-0 Cristy  <quetzlzacatenango@image...>
  * Respect throttle policy (reference
    https://github.com/ImageMagick/ImageMagick/issues/393).
  * Support the -authenticate option for PDF (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31530).

2017-03-03  6.9.7-10 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 6.9.7-10, GIT revision 11396:44b1bc6:20170303.

2017-02-21  6.9.7-10 Cristy  <quetzlzacatenango@image...>
  * Fix Spurious memory allocation message (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31438).
  * Identical images should return inf for PSNR (reference
    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31487).