further UI rendering performance improvements

indra/llrender/llfontgl.cpp

indra/llrender/llgl.cpp

indra/llrender/llgl.h

indra/llui/lllocalcliprect.cpp

indra/llui/lltextbase.cpp

indra/llui/lltextbase.h

indra/llui/lltexteditor.cpp

indra/llui/llui.cpp

indra/llui/llui.h

indra/llui/llview.cpp

indra/llui/llview.h

indra/newview/llspeakers.cpp

indra/newview/llstatusbar.cpp

indra/newview/llstatusbar.h

indra/newview/llviewernetwork.cpp

indra/newview/llviewernetwork.h

indra/newview/skins/default/xui/en/panel_chat_header.xml