Fixed exit in usr/sbin/rear when getopt failed

[jsmeix]

• Type: Bug Fix

• Impact: Normal

• How was this pull request tested?

By me on my openSUSE Leap 15.0 system.
Before:

# usr/sbin/rear -Q dump
rear: invalid option -- 'Q'
# Begin dumping out configuration and system information:
...

(i.e. the 'dump' workflow is run).
With the fix here:

# usr/sbin/rear -Q dump
rear: invalid option -- 'Q'
Use 'rear --help' or 'man rear' for more information.

• Brief description of the changes in this pull request:

In the code before in usr/sbin/rear

readonly OPTS="$( getopt -n $PROGRAM -o "c:C:dDhsSvVr:" -l "help,version,debugscripts:" -- "$@" )"
if test $? -ne 0 ; then
    echo "$help_note_text"
    exit 1
fi

the $? does not contain the getopt exit code
but the readonly return code which is always zero.
The new code

if ! OPTS="$( getopt -n $PROGRAM -o "c:C:dDhsSvVr:" -l "help,version,debugscripts:" -- "$@" )" ; then
    echo "$help_note_text"
    exit 1
fi
readonly OPTS

fixes that.
In general using $? is problematic, cf. the StopIf... functions
#2013 (comment)

[jsmeix]

If there are no (furious ;-) objections
I would like to merge it tomorrow afternoon.