kernel - Fix crypto boots and rescue boots
* The kernel text+data+bss is too big, the loader's 64MB heap can't fit
it plus modules plus the initrd image any more. Fix by reducing the
kernel's BSS.
* Reduce the BSS allocation for CPU_prvspace[] from 11MB (45056 x 256 cpus)
to ~45056 for the BSP and dynamically allocate the globaldata space for
the APs. Also saves ~11MB of ram or so on normal systems.
* Reduce the BSS allocation for cpu_map_entry_init[]. Only the BSP needs
MAXCPU+1 pre-cached vm_map_entry structures. The APs can make due with
8 or so before the VM system comes up sufficiently to dynamically allocate
these structures. This saves around ~6.5MB of ram on normal systems.