fix(storage): build with MSVC+x86

[coryan]

This change is 

[google-cloud-cpp-bot]

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[codecov]

Codecov Report

Merging #7323 (aa90307) into main (5b6c09b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #7323   +/-   ##
=======================================
  Coverage   93.65%   93.66%           
=======================================
  Files        1348     1348           
  Lines      116747   116747           
=======================================
+ Hits       109344   109350    +6     
+ Misses       7403     7397    -6     

Impacted Files	Coverage Δ
google/cloud/storage/version.h	100.00% <ø> (ø)
google/cloud/pubsub/publisher_connection_test.cc	100.00% <100.00%> (ø)
google/cloud/pubsub/samples/samples.cc	91.97% <0.00%> (-0.08%)	⬇️
google/cloud/pubsub/subscriber_connection_test.cc	97.91% <0.00%> (+0.69%)	⬆️
...le/cloud/storage/internal/curl_download_request.cc	89.25% <0.00%> (+0.74%)	⬆️
...torage/examples/storage_service_account_samples.cc	97.64% <0.00%> (+1.17%)	⬆️
google/cloud/grpc_error_delegate.cc	100.00% <0.00%> (+4.16%)	⬆️

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[google-cloud-cpp-bot]

Google Cloud Build Logs
For commit: aa903077b5de6dabc97732b92c51921507c6f038

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