ci: use incremental build in ci

[kt3k]

This PR enables the incremental build of rust code in CI by the following changes:

• Enables it by env var CARGO_INCREMENTAL=1. (release profile has incremental = false setting by default.)
• Uses matrix.kind in part of cache key because test_release and test_debug can't share the cache.
• Restores each source file's timestamp based on git log. ( ./tools/restore_mtime.py )
  • git doesn't store timestamp of files, and cargo triggers rebuild of source file based on timestamps. So we need to preserve timestamp of each file somehow. I found this script (this script restores the timestamp of files based on commit log), and it seems working.

I tested this setting in my detached fork. windows job passed in 11 minutes https://github.com/kt3k/deno_ci_test/runs/2285441107

[bartlomieju]

I believe this comment still stands - maybe we shouldn't go with depth 5 but 1 or 2 is highly desired

[kt3k]

0 means disabling shallow clone i.e. fetching all history. (this is needed for updating the modified timestamps based on git history) ref: https://github.com/actions/checkout#checkout-v2

So I'll update the comment.

[piscisaureus]

I think you should also do this for submodules. Currently only files from the "root" git repo get treated.

[piscisaureus]

We can think of ways to make this even better, but let's land it as-is first and enjoy the 2x reduction in CI build time immediately.

[piscisaureus]

@bartlomieju You have the final say.

[bartlomieju]

We can think of ways to make this even better, but let's land it as-is first and enjoy the 2x reduction in CI build time immediately.

Let's go 🚀

[ry]

LGTM - thank you Yoshiya!