inet_aton(), like inet_pton(), is in -lsocket in Solaris and possibly

inet_aton(), like inet_pton(), is in -lsocket in Solaris and possibly
other SVR4-flavored UN*Xes; search for it the same way we search for
inet_pton().

Note that, while that fixes the Solaris build, this probably still
wouldn't build on a platform without inet_aton() (if any such exist),
and might have problems with platforms lacking other functions (as they
handle this similarly).

git-svn-id: http://anonsvn.wireshark.org/wireshark/trunk@26221 f5534014-38df-0310-8fa8-9805f1628bb7