external const definition moved to headers?

[cgolchert]

Is there a reason why INVALID_IDX and COORD_OFFSETS are not defined in the header?

util.h:

OPENVDB_API extern const Index32 INVALID_IDX;

/// @brief coordinate offset table for neighboring voxels
OPENVDB_API extern const Coord COORD_OFFSETS[26];

Why do we need a .cc file for just "const Index32 INVALID_IDX = std::numeric_limits<Index32>::max();" and a handful of coords?

I have seen linking errors since v5 because it wasn't seeing util.cc for some reason.