until we support symlinks lxstat is identical to stat

Create a central place the managed the console driver (just isa-serial for
now), and exposes them as a device file and to the debug output routines.

This is the low-level console abstraction and should deal in the
char * hardware format.  The upper layer (debug.cc) already handles
all conversion from std::string and boost formats.

Destroy the drivers on OS reset (currently just call it from the loader directly) It fixes the issue of gdb breakage w/ the drivers

We now have a common set of flags for C and C++, but also allow C-only flags,
which are used to:

  a) enable C99+GNU mode
  b) include the libc internal headers

although the latter could be refined even more.

Import the whole string library, as well as the ctype functions from the musl
C library.  Must is a BSD licensed library that aims to be API and mostly ABI
compatible with glibc, so it's our easiest way to provide the ABI we need
without reinventing the wheel.  I will import more of the traditional non-syscall
C library code from it and expect libc/ to eventually mostly consist of slightly
modified musl code.

After my recent test suite changes tests are expected in /tests

Lots of work towards enabling pthread_cond_timedwait()

Conflicts:
	bootfs.manifest
	build.mak
	loader.cc

thread::wake() may be called from an interrupt handler (clockevents).

The thread that's doing the waking is obviously running, so no need to
reschedule, and it's awkward if done from an interrupt.

Thread timers can be set to wake a thread at a specified time, or cancelled.

Not yet preemption safe.

Fox simplicity, the first mutex implementation will not be compatible with
PTHREAD_MUTEX_INITIALIZER, so wrap the mutex class with a structure that also
contains an intitialization flag, and initialize it on demand.

Missed adding the object base.

It's actually percpu, but we don't have percpu support yet.  So make it
global.

Way too noisy

Allow the clockevents driver to use it during startup.

This is intentionally simplistic, supporting only one callback (intended
for waking up threads).

Use:

   with_lock(irq_lock, [] {
      stuff done with interrupts disabled, including early return stmts
   });