fix reversal of logic I introduced with my last patch

Submitted by:	Ilya A. Kriveshko <ilya@kaon.com>


git-svn-id: https://svn.apache.org/repos/asf/ant/core/trunk@269955 13f79535-47bb-0310-9956-ffa450edef68

src/main/org/apache/tools/ant/taskdefs/optional/Cab.java

@@ -90,8 +90,6 @@ public class Cab extends MatchingTask {
     
     protected String archiveType = "cab";
 
-    private static String myos;
-
     private FileUtils fileUtils = FileUtils.newFileUtils();
 
     /**
@@ -288,8 +286,7 @@ public class Cab extends MatchingTask {
 
         log("Building "+ archiveType +": "+ cabFile.getAbsolutePath());
 
-        // we must be on Windows to continue
-        if (Os.isFamily("windows")) {
+        if (!Os.isFamily("windows")) {
             log("Using listcab/libcabinet", Project.MSG_VERBOSE);
             
             StringBuffer sb = new StringBuffer();