Re: [PATCH v3] ci: run `make sparse` as part of the GitHub workflow

"Johannes Schindelin via GitGitGadget" [off-list ref]
writes:

From: Johannes Schindelin <redacted>

Occasionally we receive reviews after patches were integrated, where
`sparse` (https://sparse.docs.kernel.org/en/latest/ has more information
on that project) identified problems such as file-local variables or
functions being declared as global.

By running `sparse` as part of our Continuous Integration, we can catch
such things much earlier. Even better: developers who activated GitHub
Actions on their forks can catch such issues before even sending their
patches to the Git mailing list.

This addresses https://github.com/gitgitgadget/git/issues/345

Note: Not even Ubuntu 20.04 ships with a new enough version of `sparse`
to accommodate Git's needs. The symptom looks like this:

    add-interactive.c:537:51: error: Using plain integer as NULL pointer

To counter that, we download and install the custom-built `sparse`
package from the Azure Pipeline that we specifically created to address
this issue.

Helped-by: Jeff King [off-list ref]
Signed-off-by: Johannes Schindelin <redacted>
---

OK, this is with Peff's "oh, we need 'apt-get update' to avoid stale
package list" fix already rolled in?  It seems you took both of them,
and they look good to me, too.

Unfortunately, ci-make-sparse has already been in 'next' for the
past week or so, so incrementals are vastly preferred.

Let me squish in your "Acked-by" to both of Peff's patches and queue
them on top of js/ci-make-sparse topic.

Thanks.