Fix crash when browsing bluetooth device.

When trying to browse a N900 it crashed here because pathA was empty. Which
lead to index = maxIndex beeing -1 and pathA.at(index) crashing.

Reorder the while condition to prevent that courtesy of tsdgeos.

(cherry picked from commit f0c90a47de)

src/kitemviews/kfileitemmodel.cpp

@@ -1499,7 +1499,7 @@ int KFileItemModel::expandedParentsCountCompare(const ItemData* a, const ItemDat
     if (index > maxIndex) {
         index = maxIndex;
     }
-    while ((pathA.at(index) != QLatin1Char('/') || pathB.at(index) != QLatin1Char('/')) && index > 0) {
+    while (index > 0 && (pathA.at(index) != QLatin1Char('/') || pathB.at(index) != QLatin1Char('/'))) {
         --index;
     }