The tag is present in Lintian version 2.104.328. That is the most recent version we know about.
The following file is an old style config file, used to retrieve information about installed libraries in the system. It is typically used to compile and link against one or more libraries.
Using this kind of system to pass compile file is obsolete and will likely introduce bugs in a multi-arch system. Particularly, this kind of script could only belong to a package that is not Multi-Arch.
You should consider to move to pkg-config file and warn your user to not use this script, and open a bug upstream.
You should also consider to implement this file as a compatibility wrapper over pkg-config.
After fixing every reverse depends of your package and use pkg-config reverse depends makefile, you should consider to put this script, as a temporary convenience of your users, under /usr/lib/$DEB_HOST_MULTIARCH/$PACKAGE/bin where $DEB_HOST_MULTIARCH is the multi-arch triplet and $PACKAGE is the package name. You should also consider to add a NEWS.Debian entry.
Please refer to the pkg-config(1) manual page and http://sources.debian.net/src/imagemagick/8:126.96.36.199-6/debian/NEWS/ for details.