Update CMake to Support AS Hosts (#280)

Author: CodaFi

cmake/modules/SwiftSupport.cmake

@@ -8,10 +8,13 @@
 function(get_swift_host_arch result_var_name)
   if("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "x86_64")
     set("${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 MATCHES "aarch64|ARM64|arm64")
+    if(NOT DEFINED CMAKE_OSX_DEPLOYMENT_TARGET OR
+        "${CMAKE_OSX_DEPLOYMENT_TARGET}" STREQUAL "")
+      set("${result_var_name}" "aarch64" PARENT_SCOPE)
+    else()
+      set("${result_var_name}" "arm64" PARENT_SCOPE)
+    endif()
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "ppc64")
     set("${result_var_name}" "powerpc64" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "ppc64le")
@@ -20,10 +23,10 @@ function(get_swift_host_arch result_var_name)
     set("${result_var_name}" "s390x" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "armv6l")
     set("${result_var_name}" "armv6" PARENT_SCOPE)
-  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "armv7l")
-    set("${result_var_name}" "armv7" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "armv7-a")
     set("${result_var_name}" "armv7" PARENT_SCOPE)
+  elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "armv7l")
+    set("${result_var_name}" "armv7" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "AMD64")
     set("${result_var_name}" "x86_64" PARENT_SCOPE)
   elseif("${CMAKE_SYSTEM_PROCESSOR}" STREQUAL "IA64")