github/workflows: print clippy output in case of errors

[stefano-garzarella]

In the unsafe-check job, if cargo clippy fails, we don't have any log since we are redirecting the stderr to a file to count the number of undocumented unsafe blocks.

We don't expect it to fail, since other steps in check job should check this case, but it has happened in some cases.

Print the file content in case of cargo clippy returns with error, so we can debug better CI failures.

[osteffenrh]

Could also do cargo clippy ... > file || ( cat file; exit 1) to keep the CI pipeline behavior the same and stop if the command fails and not have it execute the remaining commands. But it is also fine as it is, I guess.

[stefano-garzarella]

Could also do cargo clippy ... > file || ( cat file; exit 1) to keep the CI pipeline behavior the same and stop if the command fails and not have it execute the remaining commands. But it is also fine as it is, I guess.

I'm not expecting cargo clippy failing (at least if it fails, it should fail also on the Check jobs), but I see your point I'll do that, thanks!