Merge downstream code and become 3.7.20

.hgtags

autobuild.xml

indra/cmake/00-COMPILE-LINK-RUN.txt

indra/llcorehttp/README.Linden

indra/llcorehttp/_httpinternal.h

indra/llcorehttp/_httplibcurl.cpp

indra/llcorehttp/_httplibcurl.h

indra/llcorehttp/_httpoperation.cpp

indra/llcorehttp/_httpoprequest.cpp

indra/llcorehttp/_httppolicy.cpp

indra/llcorehttp/_httppolicy.h

indra/llcorehttp/_httppolicyclass.cpp

indra/llcorehttp/_httpservice.cpp

indra/llcorehttp/examples/http_texture_load.cpp

indra/llcorehttp/httpcommon.cpp

indra/llcorehttp/httprequest.h

indra/llmessage/CMakeLists.txt

indra/llmessage/llcorehttputil.cpp

indra/llmessage/llcorehttputil.h

indra/llmessage/llhttpconstants.cpp