Currently, we have an atomic _waiting state for a thread, and additional
non-atomic _on_runqueue and _terminated states.  This is problematic since
a ->wake() racing with a ->stop_wait() can cause a thread to be
simultaneously running and queued.

Fix by using a single atomic variable for all theses states.

'osv thread' mucks around cpu registers, restore them before resuming the
guest.

This command allows the developer to switch to and examine an osv thread.

Detect running threads by checking whether any cpu's rsp is within the thread
stack.  If so, the thread is running on that cpu, and the saved context is
ignored as stale.  This improves 'osv info threads' greatly.

It doesn't work all that well for threads taking interrupts though.

We'll collect more osv state there.

(but don't wait for it)

Removed by 9fe982be, likely by accident.

Still with minimal stack, no interrupt support, etc.

Look up the build directory from the running object.

'osv info threads'
'osv thread apply all' (most useful with 'backtrace')

At present, a single command is available, "setargs".

   scripts/imgedit.py setargs /path/to/image arg0 arg1 arg2...

to set the boot arguments.

Java likes upper case in class file names.

Break long lines

Cuts boot time dramatically

Since we're loading multiple objects, we need to load symbol tables for all
of them.  The base addresses are no longer static (esp. after we started
loading mulitple payloads, so we need to read them from the image).

A new command is added for this: 'osv syms'.  It will try to locate symbol
tables for anything that has been loaded at this stage.

(gdb) osv heap

We no longer put any useful information on the VGA device.

Describe all sections to gdb, so it can resolve data object addresses
correctly.

This avoids problems with multiple jvm versions (for example due to OS
updates)

gives more power and is more maintainable