ksh93: update to 1.0.4.

Main changes between 1.0.3 and 1.0.4:

- Fixed multiple scoping-related bugs in the += additive assignment
  operator.
- A number of crashing bugs have been fixed.
- Various fixes for the Haiku operating system, notably 'ulimit -a'
  now works.
- Fixed the expansion of out-of-range \n back references in the
  string part of ${parameter//pattern/string}. For example:
v=AB; echo "${v/@(A)B/\0:\1:\2}"
  now yields 'AB:A:' instead of 'AB:A:\2'.
- Fixed quoted '!', '^' and '-' within [bracket] expressions in
  glob patterns; single or double quotes failed to disable their
  operator behaviour.
- Fixed a bug introduced on 2021-04-04 that incorrectly allowed
  'typeset' to turn off the readonly and export attributes on a
  readonly variable.
- In the emacs line editor, the Ctrl+R reverse-search prompt is
  now visually distinct from a literal control character ("^R: "
  instead of "^R").
- In the vi line editor, fixed the behaviour of 'C', 'c$' and 'I'
  to be consistent with standard vi(1) and with Bolsky & Korn
  (1995, p. 121).
- Aliases for many GNU long options have been added to the
  /opt/ast/bin built-in commands. Additionally, 'kill -s' now has
  a --signal long option alias compatible with the util-linux
  option.
- Backported support for 'print -u p' from ksh 93v- for
  compatibility with scripts written for 93v-/ksh2020 (this is
  equivalent to 'print -p').

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