Fix default sudo umask
Fix default sudo umask

The coverage builder is based on Ubuntu and this block should
have been added there.  It was intentionally not added to the
other distributions in unlikely event the option isn't supported
by the version of sudo installed.

Signed-off-by: Brian Behlendorf <32d50ad1e384dcb9a5bf7e40fa470df5dabaf348@llnl.gov>
zfsonlinux/zfs-buildbot,gmelikov/zfs-buildbot,zfsonlinux/zfs-buildbot,gmelikov/zfs-buildbot