Update ios.toolchain.cmake

Remove the now 8-year-old-removal of the flag "CMAKE_XCODE_EFFECTIVE_PLATFORMS" erroneously used in the mac catalyst builds.

Author: leetal

ios.toolchain.cmake

@@ -547,7 +547,7 @@ endif()
 if(CMAKE_GENERATOR MATCHES "Xcode" AND PLATFORM_INT MATCHES "^MAC_CATALYST")
   set(CMAKE_XCODE_ATTRIBUTE_CLANG_CXX_LIBRARY "libc++")
   set(CMAKE_XCODE_ATTRIBUTE_SUPPORTED_PLATFORMS "macosx")
-  set(CMAKE_XCODE_EFFECTIVE_PLATFORMS "-maccatalyst")
+  set(CMAKE_XCODE_ATTRIBUTE_SUPPORTS_MACCATALYST "YES")
   if(NOT DEFINED MACOSX_DEPLOYMENT_TARGET)
     set(CMAKE_XCODE_ATTRIBUTE_MACOSX_DEPLOYMENT_TARGET "10.15")
   else()