This patch turns on the flag which switches all our code to use the
lock-free mutex instead of the spinlock-based mutex.

It's time we start using the lock-free mutex, which is stable enough by
now - but please let me know if you do experience any performance problem,
or bugs, related to the new mutex.

If you need to disable the new mutex temporarily and return to the old,
just change the "#define LOCKFREE_MUTEX" in osv/mutex.h to #undef.

Returning a void does nothing, and just confusing.

Eclipse recognizes .mk as a makefile, make it easier for new users to
use eclipse.

This single Java source file is a full-fledged HTTP 0.9 server.
I wanted to add it to expose the console lock bug (fixed in a separate
patch), and to verify that bind() works correctly (it does).

But additionally, this tiny HTTP server (about 6KB of compressed bytecode)
can be very useful for our CLI - it can be run in the background and let
you view files in the OSV system in your browser, even while another
program is running.

To run Shrew from the CLI, just run

	java com.cloudius.cli.util.Shrew

Which runs the HTTP server in the background (in a separate thread),
letting the user continue to use the CLI. If you add an argument "fg" to
this command, it runs the server in the current thread, never returning.

Currently, the HTTP server is written to browse OSV's root directory
hierarchy: accessing http://192.168.122.100:8080/ from the host shows
you the OSV guest's root directory, and you can decend into more
directories and download individual files.

Instead of defining a command object in one file and registering it in
another, do everything in one place.

- per-cpu variables
- per-cpu kvmclock
- tracepoint probe functions
- tracepoint Java API
- 'perf stat' cli command

Usage:

  perf list (lists all tracepoints)
  perf stat tp... (counts tracepoints)

Example:

[/]$ perf stat mutex_lock ctxsw=sched_switch mutex_unlock wake=sched_wake
  mutex_lock   ctxsw  mutex_unlock    wake
          40       3          1909       2
        2075     147           190      82
         193     138           193      78
         146     139           146      92
         317     179           317      78
         146     139           146      78
         146     139           186      78
         205     139           165      78
         146     139           146      78
         146     139           146      78
         146     139           146      80
         193     143           193      81
         151     147           151      78
         146     139           146      78
         146     139           146      78
         146     139           146      78
         159     139           159      78
         149     139           149      78
         146     139           146      78
         164     139           164      78
         146     139           176      78
         176     139           146      78
         149     139           149      78
         146     139           146      78
         146     139           146      78
  mutex_lock   ctxsw  mutex_unlock    wake
         146     139           146      79
         715     147           715      80
         188     139           204      78

Don't actually implement it either yet, but at least don't abort.

We already get these from our API version of <sys/mount.h>

We don't use this header for user APIs and they conflict with the ones
from sys/mounts.h

java.lang.Math will override JavaScript's Math object.

Exposes tracepoints and counters

Add a facility to run functions when a tracepoint is hit.  This is independent
of logging; you can add a probe function with logging disabled or enabled.

The kvmclock ABI requires it to calculate system time using values for the cpu
it is running on.

Do this by:
  - changing the system time structure to be per-cpu
  - adding a cpu notifier so that per-cpu MSRs are initialized for each cpu
  - hacking around initialization order issues

cpu notifiers are called whenever a cpu is brought up (and one day, down), so
that drivers that manage the cpu (for example, kvmclock) can initialize
themselves.

The callback is called on the cpu that is being brought up.

Per-cpu variables can be used from contexts where preemption is disabled
(such as interrupts) or when migration is impossible (pinned threads) for
managing data that is replicated for each cpu.

The API is a smart pointer to a variable which resolves to the object's
location on the current cpu.

Define:

   #include <osv/percpu.hh>

   PERCPU(int, my_counter);
   PERCPU(foo, my_foo);

Use:

   ++*my_counter;
   my_foo->member = 7;

console:init() calls wake() but the scheduler is not fully initialized at this
point, disable preemption as soon as main_cont starts and disable it after smp_launch()

avoids some spurious wakes to the callout thread