debug: respect configured build tags/flags

[robberphex]

go v1.17 support multi -gcflags. Removing of gcflags is not necessary and harmful to user experience.

[google-cla]

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[robberphex]

@googlebot I signed it!

[gopherbot]

This PR (HEAD: d495a1a) has been imported to Gerrit for code review.

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[gopherbot]

Message from Go Bot:

Patch Set 1:

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Next steps:
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Please don’t reply on this GitHub thread. Visit golang.org/cl/351173.
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[gopherbot]

Message from Hyang-Ah Hana Kim:

Patch Set 1:

(1 comment)

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Please don’t reply on this GitHub thread. Visit golang.org/cl/351173.
After addressing review feedback, remember to publish your drafts!