modern iptables and debhelper build-dependencies
This series of 3 patches allows collectd to build without iptables-dev, instead preferring libip4tc-dev and libip6tc-dev.
I've tested the first two patches by building it with pbuilder, and installing the resulting package. The output log indicates that iptables-dev is not installed (while libiptc-dev is).
The first patch modernizes the debhelper-compat dependency, and drops the old-style debian/compat change. The dbgsym migration appears to require the newer debhelper version.
The second patch trivially adjusts the dependencies to libiptc-dev, which ships libiptc.pc. The current version of collectd in the repositories requires this pkg-config file.
The third patch addresses a lintian override that needed to be updated.
This should address and close debian BTS#951088.