vzlist.c: fix compiler warning and a minor error

Added needed include to get rid of the following warning:
  vzlist.c: In function ‘invert_ip’:
  vzlist.c:1084: warning: implicit declaration of function ‘inet_ntop’

Amazingly after a fix a new warning appears:
  vzlist.c: In function ‘invert_ip’:
  vzlist.c:1085: warning: comparison between pointer and integer

That reveals that the check for inet_ntop error return is wrong.
Fix this as well.
1 file changed