Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
Implemented some syscalls: dup(), dup2(), getdtablesize().
FileHandle is now a retainable, since that's needed for dup()'ed fd's.
I didn't really test any of this beyond a basic smoke check.
I added a dead-simple malloc that only allows allocations < 4096 bytes.
It just forwards the request to mmap() every time.
I also added simplified versions of opendir() and readdir().
