Don't create a temporary list of values for qDeleteAll

It's enough to pass QHash as an input for qDeleteAll,
it will delete all values and won't touch keys.

Change-Id: I9b00963888ac780f74eabdf59ad02890a042a0d2
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/autotest/autotestplugin.cpp

@@ -172,7 +172,7 @@ AutotestPluginPrivate::AutotestPluginPrivate()
 AutotestPluginPrivate::~AutotestPluginPrivate()
 {
     if (!s_projectSettings.isEmpty()) {
-        qDeleteAll(s_projectSettings.values());
+        qDeleteAll(s_projectSettings);
         s_projectSettings.clear();
     }