Added a thread-safe and robust wrapper for APR pools.

See http://redmine.imprudenceviewer.org/issues/590
and https://jira.secondlife.com/browse/SNOW-596

indra/newview/llappviewer.cpp

@@ -857,7 +857,7 @@ bool LLAppViewer::mainLoop()
 	//-------------------------------------------
 
 	// Create IO Pump to use for HTTP Requests.
-	gServicePump = new LLPumpIO(gAPRPoolp);
+	gServicePump = new LLPumpIO;
 	LLHTTPClient::setPump(*gServicePump);
 	LLCurl::setCAFile(gDirUtilp->getCAFile());