ant: Improve -lib, -find/-s, and -D argument completions.

completions/ant

@@ -24,12 +24,18 @@ _ant()
             COMPREPLY=( $( compgen -W '{1..10}' -- "$cur" ) )
             return 0
             ;;
-        -lib|-logger|-listener|-D|-inputhandler|-main)
+        -lib)
+            _filedir -d
+            return 0
+            ;;
+        -logger|-listener|-inputhandler|-main|-find|-s)
             return 0
             ;;
     esac
 
-    if [[ "$cur" == -* ]]; then
+    if [[ $cur == -D* ]]; then
+        return 0
+    elif [[ "$cur" == -* ]]; then
         COMPREPLY=( $( compgen -W '$( _parse_help "$1" )' -- "$cur" ) )
     else
         # available targets completion