Revert "Protect PostIt deletion by SolarMutex."

Probably there is a more prosaic explanation; though I am unable to reproduce
now whatever I try - with or without the patch.

This reverts commit 2b2c5288.

Change-Id: Ia3c1017f27d28bc228c497f34b8777b487d54fb4

sw/source/ui/docvw/PostItMgr.cxx

@@ -230,8 +230,6 @@ void SwPostItMgr::InsertItem(SfxBroadcaster* pItem, bool bCheckExistance, bool b
 
 void SwPostItMgr::RemoveItem( SfxBroadcaster* pBroadcast )
 {
-    SolarMutexGuard aGuard;
-
     EndListening(*pBroadcast);
     for(std::list<SwSidebarItem*>::iterator i = mvPostItFlds.begin(); i != mvPostItFlds.end() ; ++i)
     {