If OpenEXR is found by cmake config file, OpenEXR_VERSION is set instead of OPENEXR_VERSION

[bebuch]

Description

I use CMake with CMAKE_FIND_PACKAGE_PREFER_CONFIG. OpenEXR installs its own config files which set OpenEXR_VERSION instead of OPENEXR_VERSION.

Tests

It would be usefull to add a test pipline where CMake is called with CMAKE_FIND_PACKAGE_PREFER_CONFIG. However this is out of scope to this PR and should be done by a separate patch. Unfortunately, I don't currently have the time to familiarize myself enough to do this myself.

Checklist:

• I have read the contribution guidelines.
• (not applicable) If this is more extensive than a small change to existing code, I
  have previously submitted a Contributor License Agreement
  (individual, and if there is any way my
  employers might think my programming belongs to them, then also
  corporate).
• (not applicable) I have updated the documentation, if applicable.
• (not applicable) I have ensured that the change is tested somewhere in the testsuite
  (adding new test cases if necessary).
• My code follows the prevailing code style of this project.

[lgritz]

This is a totally reasonable change that I'm happy to accept, but I wonder if you think that instead of also setting OPENEXR_VERSION and having both spellings circulating around, it might be better to just change the uses of OPENEXR_VERSION all to OpenEXR_VERSION in order to have a uniform nomenclature?

It seems that the only places OPENEXR_VERSION is actually used is src/cmake/externalpackages.cmake and src/cmake/modules/FindOpenEXR.cmake.

[bebuch]

@lgritz I just want to let you know that I'm still going to take care of this PR and #3863. Just didn't get to it this week. But it should happen durring the next 2 weeks.

[bebuch]

I updated the patch. The Find Moduke seams to provide both OpenEXR_VERSION and OPENEXR_VERSION, so we can just use OpenEXR_VERSION in the check.

[lgritz]

@bebuch In the time since you first submitted this, we have switched to accepting all new code under Apache-2.0 license (changing from our historical use of BSD-3-Clause) and also enabled use of DCO sign-off.

Would you mind please acknowledging here (a comment in this PR is sufficient) that you are ok submitting under Apache-2.0?

And also, could you please do the sign-off so it passes the DCO check? The easiest way to do that is:

git commit --amend -s             # the -s will add the sign-off line
git push origin patch-2 --force

[bebuch]

I'm fine with submitting under Apache-2.0 license.