src/make.bat: add missing go.exe and dist.exe extensions

[l-we]

'go' is not an internal or external command, nor is it a runnable program
'disk' is not an internal or external command, nor is it a runnable program

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here (e.g. I signed it!) and we'll verify it.

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• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

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[l-we]

I signed it!

[googlebot]

CLAs look good, thanks!

[gopherbot]

Message from Gerrit User 5976:

Patch Set 1:

Congratulations on opening your first change. Thank you for your contribution!

Next steps:
Within the next week or so, a maintainer will review your change and provide
feedback. See https://golang.org/doc/contribute.html#review for more info and
tips to get your patch through code review.

Most changes in the Go project go through a few rounds of revision. This can be
surprising to people new to the project. The careful, iterative review process
is our way of helping mentor contributors and ensuring that their contributions
have a lasting impact.

During May-July and Nov-Jan the Go project is in a code freeze, during which
little code gets reviewed or merged. If a reviewer responds with a comment like
R=go1.11, it means that this CL will be reviewed as part of the next development
cycle. See https://golang.org/s/release for more details.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/131397.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gerrit User 5065:

Patch Set 1: Run-TryBot+1 Code-Review+2

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/131397.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gerrit User 5976:

Patch Set 1:

TryBots beginning. Status page: https://farmer.golang.org/try?commit=16b3b775

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/131397.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gerrit User 5976:

Patch Set 1: TryBot-Result+1

TryBots are happy.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/131397.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gerrit User 12446:

Uploaded patch set 2: Commit message was updated.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/131397.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Gerrit User 12446:

Uploaded patch set 3: New patch set was added with same tree, parent, and commit message as Patch Set 2.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/131397.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR is being closed because golang.org/cl/131397 has been merged.