Backported from Viewer-Dev (14684 (b047db67c337) fix a minor memory leaking flaw for SH-895: some mild memory leaking (partially))

indra/llimage/llimageworker.cpp

@@ -40,6 +40,11 @@ LLImageDecodeThread::LLImageDecodeThread(bool threaded)
 
 // MAIN THREAD
 // virtual
+LLImageDecodeThread::~LLImageDecodeThread()
+{
+	delete mCreationMutex ;
+}
+
 S32 LLImageDecodeThread::update(U32 max_time_ms)
 {
 	LLMutexLock lock(mCreationMutex);

indra/llimage/llimageworker.h

@@ -73,6 +73,8 @@ public:
 	
 public:
 	LLImageDecodeThread(bool threaded = true);
+	virtual ~LLImageDecodeThread();
+
 	handle_t decodeImage(LLImageFormatted* image,
 						 U32 priority, S32 discard, BOOL needs_aux,
 						 Responder* responder);