[Nestedvm] Attempted to use unknown syscall: 52

[David Ehrmann]

I'm slowly making progress at getting my code to run, but I hit this error:

Attempted to use unknown syscall: 52

After some searching, I found that, at least in linux, system call 52 is 
umount2.  Oddly, my code never calls that, so I grabbed a list of every 
system call to see what it does explicitly use.  I saw two that weren't 
implemented in UnixRuntime.java: exit and time.  I'm curious why neither 
was implemented and how I could go about implementing them.

Of course, this still doesn't explain syscall 52.