s3: smbd: Fix "follow symlink = no" regression part 2.

s3: smbd: Fix "follow symlink = no" regression part 2.

Add an extra paramter to cwd_name to check_reduced_name().

If cwd_name == NULL then fname is a client given path relative
to the root path of the share.

If cwd_name != NULL then fname is a client given path relative
to cwd_name. cwd_name is relative to the root path of the share.

Not yet used, logic added in the next commit.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=12721

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
(cherry picked from commit 83e30cb48859b412b76572b6a3ba84d8fde167af)