cmake: use the LINK_OPTIONS property with CMake 3.13+

Replacing the superseded `LINK_FLAGS` in these versions.

Follow-up to 7b14449 curl#14378
Closes curl#17039

Author: vszakats

lib/CMakeLists.txt

@@ -265,8 +265,11 @@ if(BUILD_SHARED_LIBS)
     set(CMAKE_REQUIRED_LINK_OPTIONS "-Wl,--version-script=${CMAKE_CURRENT_BINARY_DIR}/libcurl.vers")
     check_c_source_compiles("int main(void) { return 0; }" HAVE_VERSIONED_SYMBOLS)
     if(HAVE_VERSIONED_SYMBOLS)
-      # Superseded by LINK_OPTIONS in CMake 3.13 and later.
-      set_target_properties(${LIB_SHARED} PROPERTIES LINK_FLAGS "${CMAKE_REQUIRED_LINK_OPTIONS}")
+      if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.13)
+        set_target_properties(${LIB_SHARED} PROPERTIES LINK_OPTIONS "${CMAKE_REQUIRED_LINK_OPTIONS}")
+      else()
+        set_target_properties(${LIB_SHARED} PROPERTIES LINK_FLAGS "${CMAKE_REQUIRED_LINK_OPTIONS}")
+      endif()
     else()
       message(WARNING "Versioned symbols requested, but not supported by the toolchain.")
     endif()