Split wait4(), setrlimit(), getrlimit(), statfs(), fstatfs(), chdir(),

Split wait4(), setrlimit(), getrlimit(), statfs(), fstatfs(), chdir(),
open(), mknod(), link(), symlink(), unlink(), lseek(), access(), stat(),
lstat(), readlink(), chmod(), chown(), lchown(), utimes(), lutimes(),
futimes(), truncate(), rename(), mkdir(), rmdir(), getdirentries(),
getdents().

Trash the 4.3BSD numeric filesystem type support in mount().

Move ocreat(), olseek(), otruncate(), ostat(), olstat(), owait(),
ogetrlimit(), and osetrlimit() to the 43bsd subtree and reimplement
using split syscalls.  Move ogetdirentries() to the subtree without
change because it is such a mess.

Convince linux_waitpid(), linux_wait(), linux_setrlimit(),
linux_old_getrlimit(), and linux_getrlimit() to use split syscalls.

The file kern/vfs_syscalls.c is now completely free of COMPAT_43 code.
I believe that execve() is the only pending split before I can tackle
stackgap usage in the linux emulator's CHECKALT{EXIST,CREAT}() macros.