Fix race condition when building multiple IDL files

[OneBlue]

Summary of the Pull Request

This change solves a build failure that happens because multiple processes write do dlldata*.c as the same time. This change solves the issue by making sure that they don't run at the same time

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[yao-msft]

Recently every time I rebuild I hit this

[Copilot]

Pull request overview

This PR attempts to address a parallel-build race involving MIDL-generated dlldata*.c by adding ordering constraints between successive IDL compilation steps in the CMake IDL helper module.

Changes:

• Add a dependency chain (DEPENDS ... ${PREVIOUS_OUTPUT}) between MIDL custom commands to force sequential execution.
• Track the prior MIDL outputs via a new PREVIOUS_OUTPUT variable.

[OneBlue]

Recently every time I rebuild I hit this

Same !

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated no new comments.