Include disabled options in the output of 'set +o'. POSIX says the output of
set +o can be used to reload previous settings, for this to work disabled
options must be printed as well or otherwise options that were set in the mean
time won't be turned off.

To avoid an excessively long output line I formatted the output to print only
six options per line.

Submitted by: Jilles Tjoelker
PR: 73500