acl_common: Avoid "#include vfs_acl_common.c"

acl_common: Avoid "#include vfs_acl_common.c"

This makes vfs_acl_common.c a subsystem of its own that acl_xattr and acl_tdb
now link against, not #include it.

This patch is a bit on the large and clumsy side, but splitting it up would
(I believe) involve a separate intermediate copy of acl_common.c.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>