freeradius2/3: Fixes to init script. (#3022)

freeradius2/3: Fixes to init script. (#3022)

This fixes two issues with the freeradius package init scripts:

- The package installs libraries in /usr/lib/freeradius{2,3}, but the
  musl dynamic linker won't find them there unless LD_LIBRARY_PATH is
  set to include this directory. This adds an appropriate env statement
  to the procd init setup.

- procd expects services to stay in the foreground, or it will be unable
  to properly shut them down again. This adds the -f flag to radiusd to
  achieve that.

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>