bpo-37201: fix test_distutils failures for Windows ARM64 (GH-13902)

diff --git a/Lib/distutils/util.py b/Lib/distutils/util.py
index 50550e1..17a94bc 100644
--- a/Lib/distutils/util.py
+++ b/Lib/distutils/util.py
@@ -40,6 +40,8 @@
             return 'win-amd64'
         if '(arm)' in sys.version.lower():
             return 'win-arm32'
+        if '(arm64)' in sys.version.lower():
+            return 'win-arm64'
         return sys.platform
 
     # Set for cross builds explicitly