Cleanup: move magic nubmers to new _httpinternal.h header file.

indra/llcorehttp/CMakeLists.txt

indra/llcorehttp/_httpinternal.h

indra/llcorehttp/_httplibcurl.cpp

indra/llcorehttp/_httplibcurl.h

indra/llcorehttp/_httpoperation.cpp

indra/llcorehttp/_httpoprequest.cpp

indra/llcorehttp/_httpoprequest.h

indra/llcorehttp/_httppolicy.cpp

indra/llcorehttp/_httppolicy.h

indra/llcorehttp/_httppolicyglobal.cpp

indra/llcorehttp/_httpservice.cpp

indra/llcorehttp/_refcounted.cpp

indra/llcorehttp/bufferarray.cpp

indra/llcorehttp/httpcommon.cpp

indra/llcorehttp/httpoptions.cpp

indra/llcorehttp/httprequest.cpp

indra/llcorehttp/httprequest.h

indra/newview/lltextureview.cpp