In the newest version, we moved from find_package(Coin) to find_package(Coin3D); the
latter being include in CMake by default (FindCoin3D.cmake).
However, apparently Coin3D does not handle the imported target
Coin::Coin correctly.
Thus, for the moment, we revert the find to Coin, to fix the inclusion
of the Inventor/C/errors/debugerror.h header file.