Hidden exception in "SalTimerProc" when exit swriter (WIN)

Only found the exception with the Debugger, when exit the swriter.
The appliction stop the SalTimer, but the own message
(SAL_MSG_TIMER_CALLBACK) is in the message-queue and restart the
timer again. After that, the SalData would be delete and then in
SalTimerProc use the SalData, then exception.

Change-Id: I8e02a38d4e741cfd31de605cb5b172b28a0909fb
Reviewed-on: https://gerrit.libreoffice.org/15649Reviewed-by: Michael Stahl <mstahl@redhat.com>
Tested-by: Michael Stahl <mstahl@redhat.com>

vcl/win/source/app/saltimer.cxx

@@ -39,6 +39,13 @@ void ImplSalStopTimer(SalData* pSalData)
     HANDLE hTimer = pSalData->mnTimerId;
     pSalData->mnTimerId = 0;
     DeleteTimerQueueTimer(NULL, hTimer, INVALID_HANDLE_VALUE);
+    MSG aMsg;
+    while (PeekMessageW(&aMsg, 0, SAL_MSG_TIMER_CALLBACK, SAL_MSG_TIMER_CALLBACK, PM_REMOVE))
+    {
+        // just remove all the SAL_MSG_TIMER_CALLBACKs
+        // when the application end, this SAL_MSG_TIMER_CALLBACK start the timer again
+        // and then crashed in "SalTimerProc" when the object "SalData" was deleted
+    }
 }
 
 void ImplSalStartTimer( sal_uLong nMS, bool bMutex )