cmd/go: enable fuzz testing on OpenBSD

[macie]

This change provides support for -fuzz flag on OpenBSD. According to #46554 the flag was unsupported on some OSes due to lack of proper testing.

Fixes: #60491

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Message from Bryan Mills:

Patch Set 1: Code-Review+1 Hold+1 Run-TryBot+1

(1 comment)

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Message from Gopher Robot:

Patch Set 1:

(1 comment)

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Patch Set 1: TryBot-Result+1

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Message from qiulaidongfeng:

Patch Set 1: Code-Review+1

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[seankhliao]

looks like the cl was merged