Adjust search for LO binary on Linux to support Arch Linux

[jan-san]

This PR makes two changes to the binary search on linux:

• the version number part of the dirname is made optional
• besides /opt, /usr/lib is added as a base directory to search for the dirname pattern

These adjustments allow the library to detect the LibreOffice installation on Arch Linux when using the libreoffice-fresh package, which installs LibreOffice to /usr/lib/libreoffice/

[GoldenReverie]

testing performed on this file change, can confirm that I no longer get the missing install error. Possibly related but also maybe not but the example code does not produce a functional PDF file as per below:

result.pdf

Tested on: DISTRIB_ID="ManjaroLinux" DISTRIB_RELEASE="24.0.0" DISTRIB_CODENAME="Wynsdey" DISTRIB_DESCRIPTION="Manjaro Linux" with Sway desktop.