STM32 GCC Unspecified RTOS error

[jeromecoutant]

Summary of changes

This is #12690 on 5.15 branch

Impact of changes

Migration actions required

Documentation

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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

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[0xc0170]

Approved by @andypowers , will go in to CI once we resolve an issue (other 2 PRs for 5.15.3 are on hold as well).

[ciarmcom]

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

[0xc0170]

CI started

[mbed-ci]

Test run: FAILED

Summary: 1 of 3 test jobs failed
Build number : 1
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-ARM-lts

[0xc0170]

CI restarted (file exist error)

[mbed-ci]

Test run: FAILED

Summary: 1 of 3 test jobs failed
Build number : 2
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-GCC_ARM-lts

[0xc0170]

restarted

[mbed-ci]

Test run: FAILED

Summary: 1 of 3 test jobs failed
Build number : 3
Build artifacts

Failed test jobs:

• jenkins-ci/mbed-os-ci_build-ARM-lts

[mbed-ci]

Test run: SUCCESS

Summary: 10 of 10 test jobs passed
Build number : 4
Build artifacts

[0xc0170]

Approved by @andypowers already, will merge now