Look for boost headers for OpenVDBs older than 12

[boberfly]

Description

Look for boost headers for OpenVDBs older than 12. I was getting issues along the lines of this:

C:\Users\bober\packages\openvdb\11.0.0\platform-windows\arch-AMD64\python-3.11\include\openvdb\math\Math.h(13,10): error C1083: Cannot open include file: 'boost/numeric/conversio
n/conversion_traits.hpp': No such file or directory [C:\dev\rpks\openimageio\3.0.9.0\build\df31b1486e506952d10f9e8ae1f90b5a2144114d\_OpenImageIO\working\OpenImageIO-3.0.9.0\build
\src\libOpenImageIO\OpenImageIO.vcxproj]

Not too sure if my approach is the best but it fixed it for me on Windows MSVC v143/VS2022. I was building against OpenVDB 11 but I didn't test older versions. OpenVDB 12 I did test and it wasn't needed.

Tests

Not too sure how to make one, it is more or less a compiling bugfix.

Checklist:

• I have read the contribution guidelines.
• I have updated the documentation, if applicable. (Check if there is no
  need to update the documentation, for example if this is a bug fix that
  doesn't change the API.)
• I have ensured that the change is tested somewhere in the testsuite
  (adding new test cases if necessary).
• If I added or modified a C++ API call, I have also amended the
  corresponding Python bindings (and if altering ImageBufAlgo functions, also
  exposed the new functionality as oiiotool options).
• My code follows the prevailing code style of this project. If I haven't
  already run clang-format before submitting, I definitely will look at the CI
  test that runs clang-format and fix anything that it highlights as being
  nonconforming.

[linux-foundation-easycla]

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• ✅ login: boberfly / name: Alex Fuller (12d2b01)

[lgritz]

should be VERSION_LESS

[lgritz]

I'm tempted to think that the extra logic here should instead all be going inside FindOpenVDB.cmake.

[lgritz]

Well, that kind of backfired, now it's failing a bunch of tests. I'm not quite sure why.

[lgritz]

Suggested change

	checked_find_package (Boost)
	find_package (Boost)

I think it's failing because checked_find_package is not recursion-safe.

[lgritz]

Yeah, definitely. I can see how the checked_find_package is not at all safe to be called recursively.

So we either need to use find_package here instead of checked_find_package, or else move the boost logic back to externalpackages.cmake (sorry, maybe I steered you wrong).

[boberfly]

All good @lgritz I force-pushed the find_package approach and see what the CI will do - sorry I just got some time to get back to this, and if it doesn't work I'll put it back outside...

[lgritz]

LGTM to me now, sorry about the runaround