QDirIterator: make a confusing condition less so

The old code checked for non-empty-ness before asking whether it
contains a certain path. But an empty container cannot contain any
path.

Simply remove the isEmpty() check.

Change-Id: Ie40279a8db4900c2f7892c2a058206d622565b10
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/corelib/io/qdiriterator.cpp

@@ -319,8 +319,7 @@ void QDirIteratorPrivate::checkAndPushDirectory(const QFileInfo &fileInfo)
         return;
 
     // Stop link loops
-    if (!visitedLinks.isEmpty() &&
+    if (visitedLinks.contains(fileInfo.canonicalFilePath()))
-        visitedLinks.contains(fileInfo.canonicalFilePath()))
         return;
 
     pushDirectory(fileInfo);