fix(__parse_options): remove unneeded IFS adjustment

We needed to adjust IFS for splitting before, but we do not need it
now because we switched to `_comp_split`.  IFS is anyway adjusted by
callers `_parse_help` and `_part_usage`.

Co-authored-by: Ville Skyttä <[email protected]>

Author: akinomyoga

bash_completion

@@ -1082,8 +1082,6 @@ __parse_options()
     fi
     [[ $option ]] || return 1
 
-    local IFS=$' \t\n' # affects parsing of the regexps below...
-
     # Expand --[no]foo to --foo and --nofoo etc
     if [[ $option =~ (\[((no|dont)-?)\]). ]]; then
         option2=${option/"${BASH_REMATCH[1]}"/}