Force the use of '.' as decimal separator.
This solves issues occurring with a different decimal operator and
keeps the command line interface consistent for all locales .
E.g. zfs set quota=0.5T
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Felix Neumärker <xdch47@posteo.de>
Closes #10878