[Samba] Server-side copy support for Mac OS clients

[Andrew Berry]

Is this supposed to be supported in Samba 4.7.1? Server side copies work
fine using a Windows client. From mac OS 10.13.2, there's a full
transfer of a file being copied.

$ smbutil statshares -a

==================================================================================================
SHARE                         ATTRIBUTE TYPE                VALUE
==================================================================================================
test-share
                              SERVER_NAME                   server.lan
                              USER_ID                       501
                              SMB_NEGOTIATE                
                              SMBV_NEG_SMB1_ENABLED
                              SMB_NEGOTIATE                
                              SMBV_NEG_SMB2_ENABLED
                              SMB_NEGOTIATE                
                              SMBV_NEG_SMB3_ENABLED
                              SMB_VERSION                   SMB_3.02
                              SMB_SHARE_TYPE                DISK
                              SIGNING_SUPPORTED             TRUE
                              EXTENDED_SECURITY_SUPPORTED   TRUE
                              LARGE_FILE_SUPPORTED          TRUE
                              CLIENT_REQUIRES_SIGNING       TRUE
                              FILE_IDS_SUPPORTED            TRUE
                              DFS_SUPPORTED                 TRUE
                              FILE_LEASING_SUPPORTED        TRUE
                              MULTI_CREDIT_SUPPORTED        TRUE
                              ENCRYPTION_SUPPORTED          TRUE
                              SIGNING_ON                    TRUE

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-- 
  Andrew Berry