Public RPC server interfaces become cluttered when internal
XDR implementation details leak into them. The procedure count,
maximum XDR buffer size, and per-CPU call counters serve no
purpose outside the code that encodes and decodes NLM protocol
messages. Exposing these values through global headers creates
unnecessary coupling between the RPC dispatch logic and the
XDR layer.

Relocating the svc_version structure definitions confines this
implementation information to the files where XDR encoding and
decoding occur. In svc.c, the buffer size computation now reads
vs_xdrsize from the version structures rather than relying on a
preprocessor constant. This calculation occurs at service
initialization, after the linker has resolved the version
structure definitions. The dispatch function becomes non-static
because both the version structures and the dispatcher reside in
different translation units.

The NLMSVC_XDRSIZE macro is removed from xdr.h because buffer
size is now computed from the union of XDR argument and result
structures, matching the pattern used in other RPC services.
Version 1 and 3 share the same procedure table but maintain
separate counter arrays. Version 4 remains separate due to its
distinct procedure definitions.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

The lockd subsystem unnecessarily exposes internal NLM XDR type
definitions through the global include path. These definitions
are not used by any code outside fs/lockd/, making them
inappropriate for include/linux/lockd/.

Moving xdr.h to fs/lockd/ narrows the API surface and clarifies
that these types are internal implementation details. The
comment in linux/lockd/bind.h stating xdr.h was needed for
"xdr-encoded error codes" is stale: no lockd API consumers use
those codes.

Forward declarations for struct nfs_fh and struct file_lock are
added to bind.h because their definitions were previously pulled
in transitively through xdr.h. Additionally, nfs3proc.c and
proc.c need explicit includes of filelock.h for FL_CLOSE and
for accessing struct file_lock members, respectively.

Built and tested with lockd client/server operations. No
functional change.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>