Create the kern_fstat() and kern_ftruncate() in-kernel syscalls.

Create the kern_fstat() and kern_ftruncate() in-kernel syscalls.

Implement fstat(), nfstat() and ftruncate() using the in-kernel syscalls.

Move ofstat() and oftruncate() to the 43bsd emulation tree and implement
with in-kernel syscalls.

Create the linux_ftruncate() syscall in the linux emulation layer.  This
replaces a direct use of oftruncate() in the linux syscall map.  Rewrite
linux_newfstat() and linux_fstat64() with the in-kernel syscalls.