message: fix curl dependency on non-standard install prefix
  * fix curl dependency on non-standard install prefix
  When `libcurl` is installed to a non-standard install prefix `azure-core` will configure include/lib directories correctly (as long as `CMAKE_FIND_ROOT_PATH` is set appropriately) for its dependencies (`INTERFACE`) but not for itself (`PRIVATE`), thus failing the build.
diff: @@ -21,6 +21,7 @@ az_vcpkg_integrate()
  find_package(Threads REQUIRED)
  +if(BUILD_TRANSPORT_CURL)
  # min version for `CURLSSLOPT_NO_REVOKE`
  # https://curl.haxx.se/libcurl/c/CURLOPT_SSL_OPTIONS.html
  set(CURL_MIN_REQUIRED_VERSION 7.44)
  @@ -29,6 +30,7 @@ if(NOT CURL_FOUND)
  find_package(CURL ${CURL_MIN_REQUIRED_VERSION} REQUIRED)
  endif()
  message("Libcurl version ${CURL_VERSION_STRING}")
  +endif()
  # Storage requires 3.6.0 version for using `contains` feature
  set(NLOHMANN_JSON_MIN_REQUIRED_VERSION 3.6.0)
  @@ -118,8 +120,11 @@ create_code_coverage(core azure-core azure-core-test)
  # ${CURL_INCLUDE_DIRS} needs to be public as long as we #include<curl.h> in public headers.
  target_include_directories(azure-core PUBLIC ${CURL_INCLUDE_DIRS})
  target_include_directories(azure-core INTERFACE ${nlohmann_json_INCLUDE_DIRS})
  -target_link_libraries(azure-core INTERFACE CURL::libcurl Threads::Threads nlohmann_json::nlohmann_json)
  +target_link_libraries(azure-core INTERFACE Threads::Threads nlohmann_json::nlohmann_json)
  +if(BUILD_TRANSPORT_CURL)
  + target_link_libraries(azure-core PRIVATE CURL::libcurl)
  +endif()
  if(BUILD_TRANSPORT_WINHTTP)
  SET(WIN_HTTP_LIB Winhttp.lib)
  target_link_libraries(azure-core PRIVATE ${WIN_HTTP_LIB})
  