* setfacl.c: Align more to Linux tool.
(delacl): New function to delete acl entries only.
(modacl): Drop delete functionality. Add handling of recomputing the
mask and default mask values.
(delallacl): Rename from delacl.
(setfacl): Call delacl in Delete case. Call delallacl in DeleteAll
and DeleteDef case.
(usage): Accommodate new options. Rearrange and rephrase slightly.
(longopts): Emit 'x' in --delete case. Add --no-mask and --mask
options.
(opts): Add -x and -n options.
(main): Handle -d and -x the same. Handle -n and --mask options.
Drop handling for -r option.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>