cmd/go: record the -buildmode flag in debug.BuildInfo
Fixes #53856
Change-Id: Ib533e9fbe063b74c81f6512464a4dac5e2af0ccc
GitHub-Last-Rev:
c2ae8d6f75badd55ba6cf8e093c496c9bd1baa49
GitHub-Pull-Request: golang/go#54218
Reviewed-on: https://go-review.googlesource.com/c/go/+/420937
Auto-Submit: Bryan Mills <bcmills@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: xie cui <
523516579@qq.com>