Ios compile (#784)

* try to fix build for ios

* skip cpu compile

* fix namespace

* fix namespace

* Use CMake for platform specific cpu compile

---------

Co-authored-by: Angelos Katharopoulos <a_katharopoulos@apple.com>

CMakeLists.txt

@@ -28,7 +28,6 @@ message(STATUS "Building MLX for ${CMAKE_HOST_SYSTEM_PROCESSOR} processor on ${C
 set(MLX_BUILD_ARM OFF)
 
 if (${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
-
   if (${CMAKE_HOST_SYSTEM_PROCESSOR} MATCHES "x86_64" AND ${CMAKE_HOST_APPLE})
     message(FATAL_ERROR
       "Building for x86_64 on macOS is not supported."