Optimize various loops that call getInstance repeatedly to get .end()

indra/llappearance/lltexlayer.cpp

indra/newview/llavatarrenderinfoaccountant.cpp

indra/newview/llconversationview.cpp

indra/newview/llfloatergodtools.cpp

indra/newview/llimview.cpp

indra/newview/llviewerobjectlist.cpp

indra/newview/llvoavatar.cpp

indra/newview/llvoavatarself.cpp

indra/newview/llworld.cpp

indra/newview/llworldmapview.cpp

indra/newview/pipeline.cpp

indra/newview/rlvcommon.cpp