SwModelTestBase: fix for leaking temporary files

This alone pushes down the number of created /tmp/lu* from 527 to 2
after a single run. Regression from
9b53538a076a2370df975655c8579dfe09cff09b.

Change-Id: I5ea2e3da0b89223fb32469af3d59a2a3b246d00f
Helped-by: Markus Mohrhard <markus.mohrhard@googlemail.com>

sw/qa/extras/inc/swmodeltestbase.hxx

@@ -264,6 +264,8 @@ protected:
 
     void load(const char* pDir, const char* pName, bool bCalcLayout = true)
     {
+        if (mxComponent.is())
+            mxComponent->dispose();
         // Output name early, so in the case of a hang, the name of the hanging input file is visible.
         std::cerr << pName << ",";
         m_nStartTime = osl_getGlobalTimer();