ImageMagick: Use-After-Free when allocation in CheckPrimitiveExtent fails

ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 6.9.13-50 and 7.1.2-25, when an allocation fails in CheckPrimitiveExtent this can result in a heap-use-after-free and result in a crash. This issue has been patched in versions 6.9.13-50 and 7.1.2-25.