Have libcommon-sense-perl build without (fake)root

The only "reason" for using (fake)root appears to be trying to overwrite a read-only (0444) file in debian/rules. However, a simple chmod before that suffices to avoid this problem and makes it possible to use Rules-Requires-Root: no.

The resulting binary was bit-for-bit reproducible with and without (fake)root + patch when testing on ibcommon-sense-perl/3.75-2.