In commit 1a49188a694 (package/libnfc: add sub-options to enable
individual drivers), the dependency on threads was moved down to
the individual drivers that need it, and libnfc as a whole lost
that dependency.
However, the global comment was not removed. Do so now.
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>