re2: add Python Windows-on-ARM support Based on CL 63710. Fixes #537. Change-Id: Idc53c7f8683f0f09e6c24e6aa5cafbd23ce76099 Reviewed-on: https://code-review.googlesource.com/c/re2/+/63750 Reviewed-by: Alan Donovan <adonovan@google.com>