When creating a library or executable, several source files are combined
into a binary artifact that has an outbound license of its own. This test
generator allows to check if the combined source files are compatible
with the desired outbound license.

Requirements for using these tests:
- input source files must contain the SPDX-License-Information tag
- python3 must be available
- the "reuse spdx" tool must be available

An intended use case is to generate client-side and server-side code for
protocols shipped in the wayland-protocols package with qtwaylandscanner.

it only updates the database iff there's new files and is specifically
meant for post-install invocation. since cmake only installs files when
they actually changed this effectively turns repeated cmake --install
calls noop as far as database updates are concerned

this stops all sources with mimetype definitions from rebuilding the
mime database on every install even when nothing changed. it saves
literal seconds every install call

-n was introduced in 1.4 which is like 6 years old and there are no
pratcically relevant distribution versions around with older versions

This is useful if a library intends to reparse the original wayland.xml
file instead of using the pregenerated headers.

Png2Ico provides lower quality icons compared to icoutils as png2ico
predates the current icon standard.
Still lloking for png2ico prints
 * Png2Ico, Executable that converts a collection of PNG files into a Windows icon file, <https://www.winterdrache.de/freeware/png2ico/ or https://commits.kde.org/kdewin>

which confuses new users.

Without this simple space, FindTaglib doesn't appear on
the generated ecm-find-modules.7.html page.

Based on https://phabricator.kde.org/D21695

Several KDE projects use taglib, so we really need to provide a proper
find module in ECM.

AFAIK taglib-config should not be portable, so we don't try to
run it on WIN32. See also:
https://invent.kde.org/network/kio-extras/-/commit/548f525f4308810888c85f42a570139029c40618