Add support for Apple Silicon in SwiftSupport.cmake (jpsim#293)

Author: MaxDesiatov

cmake/modules/SwiftSupport.cmake

@@ -13,6 +13,8 @@ function(swift_get_host_arch result_var_name)
     set("${result_var_name}" "x86_64" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "aarch64")
     set("${result_var_name}" "aarch64" PARENT_SCOPE)
+  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "arm64")
+    set("${result_var_name}" "aarch64" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "ppc64")
     set("${result_var_name}" "powerpc64" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "ppc64le")