Prefer empty() checks to size()

indra/llappearance/llavatarjointmesh.cpp

indra/llappearance/lltexlayer.cpp

indra/llcharacter/llbvhloader.cpp

indra/llcharacter/llkeyframemotion.cpp

indra/llcommon/llcoros.cpp

indra/llcommon/llerror.cpp

indra/llcommon/llevent.cpp

indra/llcommon/llinitparam.h

indra/llcommon/llleap.cpp

indra/llcommon/llsdserialize.cpp

indra/llcommon/llstreamtools.cpp

indra/llcommon/llstring.cpp

indra/llcommon/llstring.h

indra/llcommon/lluriparser.cpp

indra/llcorehttp/_httpoprequest.cpp

indra/llmath/llvolume.cpp

indra/llmessage/llsdmessagebuilder.cpp

indra/llmessage/lltemplatemessagebuilder.cpp

indra/llmessage/lluseroperation.cpp

indra/llmessage/llxfermanager.cpp