Fix CTL build against IlmBase 2.3.0

[remia]

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

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[remia]

See this issue for more information : ampas/CTL#71

[fxcoudert]

• If we integrate this, it should go as part of the update PR itself: IlmBase 2.3.0 #32963
• We normally don't accept patches unless they are accepted by the upstream project