Improved stability of tst_qhttpsocketengine

Improved stability of tst_qhttpsocketengine

This autotest assumed that various network operations could always be
completed within 5 seconds.  Notably, it assumed that an attempt to
resolve a nonexistent hostname would always result in an error within
5 seconds.  In my testing, it usually takes 4-6 seconds to complete,
but occasionally takes as much as 13 seconds.

(cherry picked from qt4 commit c85faef67b6a7e8fcedb4ce800282d41f5b79ec1)

Change-Id: I982ecf6ebc1bb8ee2184cf5592cb2684474c870b
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>