There are too many K&R prototypes to make fixing the source practical,
hence set the supported language standard to C17 with GNU extensions.

Closes: #1096839

To fix a cosmetic warning with modern compilers.

Beware: distributions is a NULL-terminated array, not a string.

To update a deprecated Perl 4 construct.

Always use CFLAGS/LDFLAGS to prevent blhc errors.

To prevent innd from exploding on modern systemd with a very high
limit for open file descriptors.

Which was removed over 20 years ago.

To prevent a gcc warning about a possible overflow.

Closes: #1065795

Hardening support was broken in version 1:1.7.2q-47 by commit
9a19192c.

rsyslog stopped providing rules for news.* with version 8.23.0-1
uploaded in 2016, so INN needs to provide its own configuration fragment.

It was only needed for /lib/lsb/init-functions, which nowadays is provided
by sysvinit-utils (essential).

This is the modern name.