s3-smbd: Leave sys_disk_free() if dfree command is used

s3-smbd: Leave sys_disk_free() if dfree command is used

If we have a broken system which reports incorrect sizes we provide the
'dfree command'. This command makes sure Samba gets the correct values.
However after that we call the quota command which then reports the
broken values. The dfree command should take care to provide the correct
values and in case of quota's it should also calculate the quote
correctly.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=11403

Pair-Programmed-With: Michael Adam <obnox@samba.org>
Signed-off-by: Andreas Schneider <asn@samba.org>
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>
(cherry picked from commit 48a4d5a4078ff2a66dd753323d6e5d76d34b9828)