Fix a leak in ClientServerOutsideProcessSlowTest unittest

It looks like posting the delete request from custom
deleter might not deliver the actual delete to the QtcProcess
for some reason (e.g. event loop wasn't spinning anymore).

Change-Id: I4f797984e28d738015881bd0fe4f91d28f525989
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/libs/clangsupport/processhandle.h

@@ -38,7 +38,7 @@ public:
   {
       process->kill();
       process->waitForFinished();
-      process->deleteLater();
+      delete process;
   }
 };