cmake: CURL_LIBDIRS improvements (upstreamed from vcpkg)

Apply downstream patches from the vcpkg project:

- cmake: remove duplicates from `CURL_LIBDIRS`.

- cmake: set `CURL_LIBDIRS` as `INTERFACE_LINK_DIRECTORIES` for static
  libcurl.
  To support CMake <3.13, change downstream patch from:
  ```cmake
  target_link_directories(${LIB_STATIC} INTERFACE ${CURL_LIBDIRS})
  ```
  to:
  ```cmake
  set_target_properties(${LIB_STATIC} PROPERTIES [...] INTERFACE_LINK_DIRECTORIES "${CURL_LIBDIRS}")
  ```

Co-authored-by: Kai Pastor
Ref: https://github.com/microsoft/vcpkg/pull/43819

Closes #16610

CMakeLists.txt

@@ -2044,6 +2044,8 @@ if(HAVE_MANUAL_TOOLS)
   add_subdirectory(docs)
 endif()
 
+list(REMOVE_DUPLICATES CURL_LIBDIRS)
+
 add_subdirectory(lib)
 
 if(BUILD_CURL_EXE)

lib/CMakeLists.txt

@@ -149,7 +149,8 @@ if(BUILD_STATIC_LIBS)
   set_target_properties(${LIB_STATIC} PROPERTIES
     PREFIX "" OUTPUT_NAME "${LIBCURL_OUTPUT_NAME}"
     SUFFIX "${STATIC_LIB_SUFFIX}${CMAKE_STATIC_LIBRARY_SUFFIX}"
-    INTERFACE_COMPILE_DEFINITIONS "CURL_STATICLIB")
+    INTERFACE_COMPILE_DEFINITIONS "CURL_STATICLIB"
+    INTERFACE_LINK_DIRECTORIES "${CURL_LIBDIRS}")
   if(CURL_HIDES_PRIVATE_SYMBOLS)
     set_property(TARGET ${LIB_STATIC} APPEND PROPERTY COMPILE_FLAGS "${CURL_CFLAG_SYMBOLS_HIDE}")
     set_property(TARGET ${LIB_STATIC} APPEND PROPERTY COMPILE_DEFINITIONS "CURL_HIDDEN_SYMBOLS")