net/samba4: security update to 4.15.5

This is a security release in order to address the following defects:

o CVE-2021-44141: UNIX extensions in SMB1 disclose whether the outside target
                  of a symlink exists.
                  https://www.samba.org/samba/security/CVE-2021-44141.html

o CVE-2021-44142: Out-of-Bound Read/Write on Samba vfs_fruit module.
                  https://www.samba.org/samba/security/CVE-2021-44142.html

o CVE-2022-0336:  Re-adding an SPN skips subsequent SPN conflict checks.
                  https://www.samba.org/samba/security/CVE-2022-0336.html

(thor)