Use a globaldata_t instead of a cpuid in the lwkt_token structure. The

Use a globaldata_t instead of a cpuid in the lwkt_token structure.  The
LWKT subsystem already uses globaldata_t instead of cpuid for its thread
td_gd reference, and the IPI messaging code will soon be converted to take
a globaldata_t instead of a cpuid as well.  This reduces the number of
memory indirections we have to make to access the per-cpu globaldata space
in various procedures.