mksh and OpenBSD's ksh support an alternative case syntax for historical
reasons [1],

    case $i {
    *pattern) do ;;
    *pattern2) do2 ;;
    }


Currently, sh-mode cannot handle this and the easy way out of writing a
semicolon after $i is out since,

   % case "foo"; { *o) echo 1;; }
   /bin/mksh: syntax error: unexpected ';'

I came with the attached patch after a bit of trial and error but I'm
not sure if it is the right way to do it.