devel/linux-c7-systemd-libs: Bring back libudev.so?

[Gleb Popov]

I wonder if we can revert
https://github.com/freebsd/freebsd-ports/commit/516aa73ebc6276c688b7c7bcc815658ece81b583
now?
I've ported a Linux app that uses libudev.so and it works fine with it.