In b047331 kiozen fixed build on Debian-based systems by having cmake patch in Find-files for libproj and quazip if a Debian system is detected. I believe this approach is not optimal: for the case of libproj, there are more systems than only Debian-based ones which build libproj with autotools (e.g. FreeBSD: https://svnweb.freebsd.org/ports/head/graphics/proj/Makefile?revision=498655&view=markup&sortby=date#l20 and Suse-based distributions: https://sourceforge.net/p/qlandkartegt/mailman/message/36645204/ ). Instead of trying to maintain a list of distributions (and still missing systems with local installations of libproj) I propose to use pkg-config for finding libproj if and after cmake's own mechanism fail. My patch from above-linked mail implements this - I'm creating this issue mainly to make sure it doesn't get lost in that mailing list archive.
For the case of libquazip: that issue only affects current Debian Stable aka "stretch", the Debian maintainers have since added the Find file: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=778768 (a fixed version is included in Debian testing aka "buster" as of now). Providing a local Find file in qmapshack could create other problems on the newer Debian systems - I wonder if it wasn't better to require user-provided flags for libquazip in that case?