fix platform detection

Author: matcool

CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.21)
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
-if ("${GEODE_TARGET_PLATFORM}" STREQUAL "iOS" OR IOS)
+if ("${CMAKE_SYSTEM_NAME}" STREQUAL "iOS" OR IOS)
 	set(CMAKE_OSX_ARCHITECTURES "arm64")
 else()
 	set(CMAKE_OSX_ARCHITECTURES "arm64;x86_64")