Optimize access to LLViewerParcelMgr singleton

indra/newview/alavataractions.cpp

indra/newview/llagent.cpp

indra/newview/llagentui.cpp

indra/newview/llaudiosourcevo.cpp

indra/newview/llenvironment.cpp

indra/newview/lllocationinputctrl.cpp

indra/newview/llnetmap.cpp

indra/newview/llpaneltopinfobar.cpp

indra/newview/lltoolmgr.cpp

indra/newview/lltoolpie.cpp

indra/newview/llviewermedia.cpp

indra/newview/llviewermediafocus.cpp

indra/newview/llviewermessage.cpp

indra/newview/llviewerparcelmedia.cpp

indra/newview/llviewerparcelmediaautoplay.cpp

indra/newview/llviewerparcelmgr.cpp

indra/newview/llviewerwindow.cpp

indra/newview/llvoicevivox.cpp

indra/newview/rlvcommon.cpp

indra/newview/rlvui.cpp