Remove vestigial httpclient.h include from files that no longer need it.

indra/llmessage/llavatarnamecache.cpp

indra/llmessage/llcorehttputil.h

indra/newview/llagentlanguage.cpp

indra/newview/llavatarrenderinfoaccountant.cpp

indra/newview/llestateinfomodel.cpp

indra/newview/lleventpoll.cpp

indra/newview/llfacebookconnect.cpp

indra/newview/llfeaturemanager.cpp

indra/newview/llflickrconnect.cpp

indra/newview/llfloaterabout.cpp

indra/newview/llfloaterautoreplacesettings.cpp

indra/newview/llfloateravatarpicker.cpp

indra/newview/llfloaterhoverheight.cpp

indra/newview/llfloaterregiondebugconsole.h

indra/newview/llfloatertos.cpp

indra/newview/llfloaterurlentry.cpp

indra/newview/llmediadataclient.h

indra/newview/llpanelclassified.cpp

indra/newview/llpanellogin.cpp

indra/newview/llpathfindingmanager.cpp