Bug#916719: On the fix of CVE-2018-20185

[Bob Friesenhahn]

This issue (and some similar issues in the dib.c code) is addressed by 
Mercurial changeset 15880:c38fc0e3e465.

Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/
Public Key,     http://www.simplesystems.org/users/bfriesen/public-key.txt