Memory leak at server reconfiguration with GeoIP2

Previously loaded GeoIP2 databases are not released during server reconfiguration. For a server with GeoIP2 databases readily available in the default paths, this results in:

$ named
$ top -b -n1 -p $(pidof named) | tail -n 2
  PID USER      PR  NI    VIRT    RES  %CPU  %MEM     TIME+ P S COMMAND
30518 kempniu   20   0  677.1m  22.4m   0.0   0.1   0:00.03 1 S named
$ for i in {1..100}; do rndc reload > /dev/null; done
$ top -b -n1 -p $(pidof named) | tail -n 2
  PID USER      PR  NI    VIRT    RES  %CPU  %MEM     TIME+ P S COMMAND
30518 kempniu   20   0 7875.0m 103.9m   0.0   0.7   0:02.93 1 S named
$ for i in {1..100}; do rndc reload > /dev/null; done
$ top -b -n1 -p $(pidof named) | tail -n 2
  PID USER      PR  NI    VIRT    RES  %CPU  %MEM     TIME+ P S COMMAND
30518 kempniu   20   0   14.7g 167.6m   0.0   1.1   0:05.93 1 S named