Switch to fixed version of crcmod.

This won't affect anything at present, but will give us a working
wheel for mac-arm64 if that platform is later added to match_tags.

Bug: 1233745
Change-Id: Ib3126d80d488fc9170713482dede666617c23129
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3115585
Auto-Submit: Brian Ryner <bryner@google.com>
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Dirk Pranke <dpranke@google.com>

gsutil.vpython

@@ -100,7 +100,7 @@ wheel: <
 
 wheel: <
   name: "infra/python/wheels/crcmod/${vpython_platform}"
-  version: "version:1.7"
+  version: "version:1.7.chromium.2"
   match_tag: <
     abi: "cp27mu"
     platform: "manylinux1_i686"