Log Message:
Update ImageMagick to version 7.0.7.11.

Upstream changes:

2017-11-11  7.0.7-11 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.0.7-11, GIT revision 21635:0447c6b46:20171111.

2017-11-05  7.0.7-10 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.0.7-10, GIT revision 21612:36e2aabfd:20171105.

2017-11-03  7.0.7-10 Dirk Lemstra <dirk@lem.....org>
  * Fixed a problem with resource bookkeeping in AcquireMatrixInfo().

2017-10-30  7.0.7-9 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.0.7-9, GIT revision 21580:2682a311e:20171031.

2017-10-20  7.0.7-9 Cristy  <quetzlzacatenango@image...>
  * Encode JSON control characters (reference
    https://github.com/ImageMagick/ImageMagick/issues/848).

2017-10-27  7.0.7-9 Dirk Lemstra <dirk@lem.....org>
  * Added support for reading mipmaps in dds images (reference
    https://github.com/ImageMagick/ImageMagick/issues/845).