hwclock: add --ul-debug implementing debug.h

hwclock: add --ul-debug implementing debug.h

Undocumented at this time, because it is a skeleton
implementation.  More debugging points are to be added after
refactoring is complete, or ad hoc in the mean time.

When fully implemented, enough time may have passed that the
deprecated --debug could be used to replace --ul-debug.

[kzak@redhat.com: - use __UL_INIT_DEBUG_FROM_STRING() to initialize the mask
                  - add hwclock_init_debug()]

Coauthored-by: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Signed-off-by: J William Piggott <elseifthen@gmx.com>
Signed-off-by: Karel Zak <kzak@redhat.com>