message: make Curl default option to build on Win as a temp workaround
  * make Curl default option to build on Win as a temp workaround
  * Temporarily disable setting WinHTTP as a transport adapter since it
  hasn't been implemented yet, to unblock building master.
diff: # Defines `BUILD_TRANSPORT_WINHTTP_ADAPTER` and `BUILD_CURL_HTTP_TRANSPORT_ADAPTER` for source code
  if (WIN32 OR MINGW OR MSYS OR CYGWIN)
  - if(BUILD_TRANSPORT_CURL)
  add_compile_definitions(BUILD_CURL_HTTP_TRANSPORT_ADAPTER)
  - endif()
  - # Make sure to build WinHTTP either if was user-requested or no transport was selected at all
  - if(BUILD_TRANSPORT_WINHTTP OR NOT BUILD_TRANSPORT_CURL)
  - add_compile_definitions(BUILD_TRANSPORT_WINHTTP_ADAPTER)
  - SET(BUILD_TRANSPORT_WINHTTP ON)
  - endif()
  + SET(BUILD_TRANSPORT_CURL ON)
  elseif(UNIX)
  if(BUILD_TRANSPORT_WINHTTP)
  message(FATAL_ERROR "Win HTTP transport adapter is not supported for Unix platforms")
  