remove iproute2 dependency

Bugreport: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1023382

Nginx has a dependency on iproute2, uses ss to test whether TCP port 80 is already in use.

In this commit it was added: cc65b80e

Problems:

• iproute2 is an unnecessary dependency for light installations
• currently we have build problems on hurd installations, e.g.:

nginx depends on missing:
- iproute2:hurd-amd64