Papyrus has only been tested under debian, so package names may vary between distributions. A lot of these packages are used inside a bash script, so the error messages can be quite cryptic.
Check the README file in the .tar.gz for more details on dependencies. MySQL and PostgreSQL connections are handled by dynamically loaded modules, but you will have linking or runtime problems if you don't have both the postgresql and mysql development and runtime files installed.
If you want to disable one of the databases I recommend you remove that dynamic library generated by papyrus (ie libpapyrus_mysql.so) so that it won't try and link against that database.