Syscall string debugging

When CONFIG'd, allows certain syscalls to store some text in the name of
its kthread.  You can see the name of a kthread when debugging
semaphores.  Each syscall needs to have its own message, as I've done
for read and open so far.
Syscall debugging helper

Kfunc this from the monitor.  Helps when you want to know details about
a kthread sleeping on a semaphore.  If the process dies or the syscall
completes while you run this, you'll get garbage and might fault.
Fixes vcore counters

I was a little tossed up about putting the accounting in map/unmap or
not.  It'd be correct (if we did a little more unmapping for SCPs), but
in the end I wanted to parallelize the work as much as possible.  Our
'for each' vcore loops are probably long enough as it is.
Vcore timers are stored in ticks (XCC)

Convert only when we actually care about the value.  Also renames
vcore_{resume,total}.

Reinstall your kernel headers.
Monitor command: pip

Short version of "procinfo pid".  I got tired of typing it.
Proc vcore list only has available vcores

Previously, you could see up to vcore 8 on an 8 core machine, even
though you could never get that last vcore.  This commit keeps the list
of vcores in sync with which vcores are available.

Right now, the rules for max_vcores is that it is set at process
creation and never changed.  The ksched could offer a process less than
the number of CG cores in the system, via the max_vcores() function.