Allow long temp file names

Author: charris

azure/windows.yml

@@ -26,6 +26,10 @@ jobs:
         displayName: Set python version
         condition: not(contains(variables['PYTHON_VERSION'], 'PyPy'))
 
+      - powershell: |
+          Set-ItemProperty 'HKLM:\System\CurrentControlSet\Control\FileSystem' -Name 'LongPathsEnabled' -value 1
+        displayName: "Enable long path names"
+
       - powershell: |
           $url = "http://buildbot.pypy.org/nightly/py3.6/pypy-c-jit-latest-win32.zip"
           $output = "pypy.zip"