Merge cnode.h:1.25, coda_fbsd.c:1.48, coda_io.h:1.10,

Merge cnode.h:1.25, coda_fbsd.c:1.48, coda_io.h:1.10,
coda_kernel.h:1.7, coda_namecache.c:1.25, coda_namecache.h:1.14,
coda_opstats.h:1.8, coda_pioctl.h:1.10, coda_psdev.c:1.43,
coda_psdev.h:1.8, coda_subr.c:1.35, coda_subr.h:1.11,
coda_venus.c:1.30, coda_venus.h:1.11, coda_vfsops.c:1.79,
coda_vfsops.h:1.14, coda_vnops.c:1.92, coda_vnops.h:1.23 from HEAD
to RELENG_7:

  Since we're now actively maintaining the Coda module in the FreeBSD source
  tree, restyle everything but coda.h (which is more explicitly shared
  across systems) into a closer approximation to style(9).

  Remove a few more unused function prototypes.

  Add or clarify some comments.

Minor differences required in the MFC due to diverging VFS locking in
HEAD vs RELENG_7.