CVE-2020-27756

In ParseMetaGeometry() of MagickCore/geometry.c, image height and width calculations can lead to divide-by-zero conditions which also lead to undefined behavior. This flaw can be triggered by a crafted input file processed by ImageMagick and could impact application availability. The patch uses multiplication in addition to the function `PerceptibleReciprocal()` in order to prevent such divide-by-zero conditions. This flaw affects ImageMagick versions prior to 7.0.9-0.