I may be mistaken (I don't understand Italian (or whatever the language is)), but it seriously looks like you installed the Debian package from upstream and then tried to upgrade with the package in Ubuntu. I am terrible sorry to say that in general that is impossible to support.
In this case, I will try to fix it, but that fix will NOT go into Xenial Xerus as that is already frosen.
The Debian/Ubuntu package callled fpc-src never contained any files, it was always a meta package.
I may be mistaken (I don't understand Italian (or whatever the language is)), but it seriously looks like you installed the Debian package from upstream and then tried to upgrade with the package in Ubuntu. I am terrible sorry to say that in general that is impossible to support.
In this case, I will try to fix it, but that fix will NOT go into Xenial Xerus as that is already frosen.
The Debian/Ubuntu package callled fpc-src never contained any files, it was always a meta package.