@Bulli => I can share the compiled lib with you with no guarantee.
As Ninos say, best way would be to compile ProFTPd by yourself, but this can be a little "tricky".
As the related change, for this particular issue, was only change on a particular module of ProFTPd, I keep using the actual release (provided by Debian) of ProFTPd with the latest version of the module (the .SO file), it's working for me.
The main advantage there is that I'll be able to update ProFTPd using apt, and keep using those sources (and didn't break anything with i-MSCP setup).