Tracker: Fixed CachedEntryIterator::GetNextEntry() debug build.

* A "style fix" introduced in 54e2dd7272
  broke the debug version by reversing the assertion logic.

src/kits/tracker/EntryIterator.cpp

@@ -167,8 +167,8 @@ CachedEntryIterator::~CachedEntryIterator()
 status_t
 CachedEntryIterator::GetNextEntry(BEntry* result, bool traverse)
 {
-	ASSERT(fDirentBuffer != NULL);
-	ASSERT(fEntryRefBuffer != NULL);
+	ASSERT(fDirentBuffer == NULL);
+	ASSERT(fEntryRefBuffer == NULL);
 
 	if (fEntryBuffer == NULL) {
 		fEntryBuffer = new BEntry [fCacheSize];