fix macos cmake arch var to allow overriding via command line

only generate fat if compiler supports it

CMakeLists.txt

@@ -3,7 +3,25 @@ cmake_minimum_required(VERSION 3.19)
 string(REGEX REPLACE "(.*)/" "" THIS_FOLDER_NAME "${CMAKE_CURRENT_SOURCE_DIR}")
 project(${THIS_FOLDER_NAME})
 
-set(CMAKE_OSX_ARCHITECTURES x86_64;arm64)
+if (APPLE)
+    if (${CMAKE_GENERATOR} MATCHES "Xcode")
+            if (${XCODE_VERSION} VERSION_LESS 10)
+                message(STATUS "Xcode 10 or higher is required. Please install from the Mac App Store.")
+                return ()
+            elseif(${XCODE_VERSION} VERSION_GREATER_EQUAL 12)
+                set(C74_BUILD_FAT YES)
+            endif ()
+    endif ()
+
+    if (NOT CMAKE_OSX_ARCHITECTURES)
+        if(C74_BUILD_FAT)
+            set(CMAKE_OSX_ARCHITECTURES "x86_64;arm64" CACHE STRING "macOS architecture" FORCE)
+        else()
+            set(CMAKE_OSX_ARCHITECTURES "x86_64" CACHE STRING "macOS architecture" FORCE)
+        endif()
+    endif()
+    message("CMAKE_OSX_ARCHITECTURES set to ${CMAKE_OSX_ARCHITECTURES}")
+endif()
 
 MACRO(SUBDIRLIST result curdir)
   FILE(GLOB children RELATIVE ${curdir} ${curdir}/*)