Add system-specific network link flags to inet_aton test. This should fix

the check on platforms that require those flags.
patch by Michael Kostylev, mik niipt ru

Originally committed as revision 11553 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1569,7 +1569,7 @@ fi
 check_func  fork
 check_func  gethrtime
 check_func  getrusage
-check_func  inet_aton
+check_func  inet_aton $network_extralibs
 check_func  memalign
 check_func  mkstemp
 check_func2 windows.h GetProcessTimes