Restore commented-out code in QHash test.

The restored code verifies the following statement in the documentation
of QHash::find():

"If the hash contains no item with the key, the function returns end()."

It is not clear why the code was commented-out in the first place, as
this occurred before the tests were imported into the Qt repository in
2006.

Change-Id: I745393a8e3e728fc60009da07abd038a3d56e99c
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>

tests/auto/corelib/tools/qhash/tst_qhash.cpp

@@ -594,7 +594,7 @@ void tst_QHash::find()
     QString compareString;
     int i,count=0;
 
-    //QVERIFY(map1.find(1) == map1.end());
+    QVERIFY(map1.find(1) == map1.end());
 
     map1.insert(1,"Mensch");
     map1.insert(1,"Mayer");