llama : add Metal and Foundation frameworks to the xcframework

This commit adds the Metal and Foundation frameworks to the xcframework
module. This is necessary for the xcframework to be able to be used in
projects that use Metal or Foundation. I did not notice this with
projects where I added the xcframework to the project, but I did notice
this when trying out Swift Package Manager with the xcframework (I've
not committed the Package.swift file yet as there are still some
discussions in progress about this)

Author: danbev

build-xcframework.sh

@@ -71,6 +71,8 @@ framework module llama {
 
     link "c++"
     link framework "Accelerate"
+    link framework "Metal"
+    link framework "Foundation"
 
     export *
 }