tdf#99383 vcl: don't dispatch events from SolarMutexReleaser

Having SolarMutexReleaser effectively do Reschedule() on WNT and not on
other platforms doesn't seem such a good idea.  Let's try to restrict it
so that it still calls ImplSalYieldMutexAcquireWithWait() but no longer
dispatches messages, timers and idles.

(regression from 482c52e9)

Change-Id: I52a2c88e9c2473e35909bf270b9e3ae7acbe0d17

vcl/source/app/svapp.cxx

@@ -517,8 +517,11 @@ inline bool ImplYield(bool i_bWait, bool i_bAllEvents, sal_uLong const nReleased
 
     DBG_TESTSOLARMUTEX(); // must be locked on return from Yield
 
-    // Process all Tasks
-    Scheduler::ProcessTaskScheduling(eResult == SalYieldResult::EVENT);
+    if (nReleased == 0) // tdf#99383 don't run stuff from ReAcquireSolarMutex
+    {
+        // Process all Tasks
+        Scheduler::ProcessTaskScheduling(eResult == SalYieldResult::EVENT);
+    }
 
     // flush lazy deleted objects
     if( pSVData->maAppData.mnDispatchLevel == 0 )

vcl/win/app/salinst.cxx

@@ -646,7 +646,10 @@ SalYieldResult WinSalInstance::DoYield(bool bWait, bool bHandleAllCurrentEvents,
     }
     else
     {
-        eDidWork = ImplSalYield( bWait, bHandleAllCurrentEvents );
+        if (nReleased == 0) // tdf#99383 ReAcquireSolarMutex shouldn't Yield
+        {
+            eDidWork = ImplSalYield( bWait, bHandleAllCurrentEvents );
+        }
 
         n = nCount;
         while ( n )