libnfs.c: Follow symlinks during path resolution

libnfs.c: Follow symlinks during path resolution

Follow symlinks during path resolution.  If the symlink points outside
the mount, -ENOENT is returned.  This is slightly different behavior
from the in-kernel NFS client where symlinks pointing outside the mount
get resolved to local paths.

The algorithm for symlink resolution is simple and stupid.  If a symlink
is encountered, the path is rewritten and path resolution begins again
from the root filehandle.  A count is kept to prevent loops.  This is
not particularly efficient but it is good enough for now.

Signed-off-by: Ross Lagerwall <rosslagerwall@gmail.com>