Exclude tools/targets from frozen tools check

[LDong-Arm]

Summary of changes

Scripts in tools/targets are related to target support - they are technically not core parts of the old tools. To integrate the latest TF-M, we need to be able to update the post binary hook for Musca targets in that path.

#14354 depends on this.

Impact of changes

Modifications are allowed in tools/targets.

Migration actions required

None.

Documentation

None.

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Pull request type

[x] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[x] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

@Patater @ARMmbed/mbed-b-tools

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[ciarmcom]

@LDong-Arm, thank you for your changes.
@Patater @ARMmbed/mbed-os-maintainers please review.

[Patater]

We prefer to keep this area frozen, as changes to these scripts may have an impact on the online compiler or IDE. We've been approving exceptions on a case-by-case basis. Musca, which isn't supported in the online compiler, generally receives such exceptions and we merge even with Travis CI failing.

@0xc0170 can confirm we sometimes merge changes even with Travis CI failing the frozen tools check.

[Patater]

tools/targets is referenced from the online tools, so we can't remove this from the frozen check.

[LDong-Arm]

We prefer to keep this area frozen, as changes to these scripts may have an impact on the online compiler or IDE. We've been approving exceptions on a case-by-case basis. Musca, which isn't supported in the online compiler, generally receives such exceptions and we merge even with Travis CI failing.

This makes sense. But the failing of "Frozen tools check" prevents the other Travis tests from being run: https://github.com/ARMmbed/mbed-os/pull/14354/checks?check_run_id=1980968740
Those tests did pass for all TF-M v1.2 related PRs that didn't touch targets/tools, so are we okay if the final PR (merging to master) doesn't have a full Travis run?

[Patater]

so are we okay if the final PR (merging to master) doesn't have a full Travis run?

We've in the past been able to test the rest of Travis by removing the frozen files from the PR, then putting it back in before merge. That's probably not practical for the TF-M PR though.

Is it possible to have Travis CI do a full run even if frozen tools fails? I would welcome a PR to make that change.