Summary:
It looks like D86316341 caused the GitHub unit tests to stop passing since SPM relies on IGListKit and IGListDiffKit being in the same directory so there are no module imports.
This diff adds the same `__has_include` conditional checking so our internal and external module configurations will both work.
Pull Request resolved: https://github.com/instagram/IGListKit/pull/1644
Test Plan:
The external tests are working again. As long as the internal tests also pass, we should be good!
{F1983488354}
Reviewed By: m3rlin45
Differential Revision: D86943807
Pulled By: TimOliver
fbshipit-source-id: c741acbb1f8425e92834daec720d4be3b3c264da