trimMemory for unswappable objects

trimMemory for unswappable objects

Inside StoreEntry::swapOut() the StoreEntry::trimMemory() method called to
release unused MemObjects memory. The trimMemory method must called for all
store entries, but current code blocks that call for not-swappable objects,
at least.

This patch trying to fix this bug implementing the following simple logic:
   {
     bool weAreOrMayBeSwappingOut =
           swappingOut() || mayStartSwapout();

     trimMemory(weAreOrMayBeSwappingOut);

     if (!weAreOrMayBeSwappingOut)
         return; // nothing else to do
   }

This is a Measurement Factory project