QET_LANG_PATH was "l10n/" for WIN32, a value that appears nowhere else in
the tree: the MSI shortcuts pass --lang-dir="[INSTALLDIR]lang/", and the
windows-build workflow copies the .qm files into files/lang/. So the
compiled-in default pointed at a directory no packaging creates, leaving
the command-line argument to do all the work.
Align it with what is actually shipped, so the binary-relative lookup
added in the previous commit can find the translations on its own.
Those desktop MIME types were needed only with KDE up to 3.x, as it
used to have its own desktop-based MIME type system. KDE 3 is EOL for
many years now, and there are already XDG MIME types.
These files are the bare XML definitions, and they are automatically
generated by update-mime-database (part of shared-mime-info) on update
(e.g. by distro hooks) or manually. Keeping them in the sources, and
installing them, is definitely not correct, as qelectrotech.xml is
their canonical definition.
Hence, drop them from the sources, together with references to them.
ispyisail