- change natives extraction to check for space *and* writability

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@8515 75d07b2b-3a1a-0410-a2c5-0572b91ccdca

engine/src/desktop/com/jme3/system/Natives.java

@@ -64,7 +64,7 @@ public class Natives {
         }
         if (extractionDir == null) {
             File workingFolder = new File("").getAbsoluteFile();
-            if (workingFolder.getUsableSpace()>0) {
+            if (workingFolder.getUsableSpace() == 0 || !workingFolder.canWrite()) {
                 logger.log(Level.WARNING, "Working directory is not writable. Using home directory instead.");
                 extractionDir = new File(JmeSystem.getStorageFolder(),
                         "natives_" + Integer.toHexString(computeNativesHash()));