xfs_io: Make -D and -R options incompatible explicitly

xfs_io: Make -D and -R options incompatible explicitly

-D and -R options are mutually exclusive actually but many commands
can accept them at the same time and process them differently(e.g.
chattr alway chooses -D option or cowextsize accepts the last one
specified), so make these commands have the consistent behavior that
don't accept them concurrently.

1) Make them incompatible by setting argmax to 1 if commands can accept
   single option(i.e. lsattr, lsproj).
2) Make them incompatible by adding check if commands can accept multiple
   options(i.e. chattr, chproj, extsize, cowextsize).

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>