core: Fix initialization of IccProfile::s_connectionSpace
Colorimetry constants can be initialized after IccProfile::s_connectionSpace when LTO is enabled. It's okay with the C++ standard.
As a way around it, this change moves the CIEXYZD50 constant to the IccProfile where it's actually needed.
We need to reconsider how the constants are defined, e.g. have static getters or use constexpr. But as a short term solution, this should be fine.
Co-authored-by: Xaver Hugl xaver.hugl@gmail.com