checklibs needs to grep for the cfg_* prefix in lib/isccfg

(cherry picked from commit ab7356a7de)

util/checklibs.sh

@@ -93,6 +93,7 @@ do
     test -z "$dirs" && continue;
     pat=$lib
     test $lib = dns && pat='\(dns\|dst\)'
+    test $lib = isccfg && pat='cfg'
     pat="^${pat}_[a-z0-9_]*("
     list=`git ls-files -c $dirs | grep '\.h$' |
 	  xargs grep "$pat" |