ImageMagick: update to 7.0.8.42.

2019-04-29  7.0.8-42 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.0.8-42, GIT revision 15570:71190ccd0:20190424

2019-04-20  7.0.8-42 Cristy  <quetzlzacatenango@image...>
  * Fixed a number of issues (reference
    https://imagemagick.org/discourse-server/viewforum.php?f=3).
  * Fixed a number of issues (reference
    https://github.com/ImageMagick/ImageMagick/issues).

2019-04-19  7.0.8-41 Cristy  <quetzlzacatenango@image...>
  * Release ImageMagick version 7.0.8-41, GIT revision 15540:c78993d13:20190420

2019-04-13  7.0.8-41 Cristy  <quetzlzacatenango@image...>
  * Fixed a number of issues (reference
    https://imagemagick.org/discourse-server/viewforum.php?f=3).
  * Fixed a number of issues (reference
    https://github.com/ImageMagick/ImageMagick/issues).
  * Honor SOURCE_DATE_EPOCH environment variable (reference
    https://github.com/ImageMagick/ImageMagick/pull/1496/).
  * Standardize on UTC time for any image format timestamp.
  * Add MagickAutoThresholdImage(), MagickCannyEdgeImage(),
    MagickComplexImages(), MagickConnectedComponentsImage(),
    MagickHoughLineImage(), MagickKuwaharaImage(), MagickLevelizeImageColors(),
    MagickLevelImageColors(), MagickMeanShiftImage(), MagickPolynomialImage(),
    MagickRangeThresholdImage(), MagickSetSeed(), MagickWaveletDenoiseImage()
    methods to MagickWand API.

(wiz)