Fix the output of typeset -p for two dimensional indexed arrays (#454)

In ksh93v- 2012-10-04 the following bugfix is noted in the changelog
(this fix was most likely part of ksh93v- 2012-09-27, although that
version is not archived anywhere):
12-09-21  A bug in which the output of a two dimensional sparse
          indexed array would cause the second subscript be treated
          as an associative array when read back in has been fixed.
          Elements that are sparse indexed arrays now are prefixed
          type "typeset -a".

Below is a before and after of this change:

   # Before
   $ typeset -a foo[1][2]=bar
   $ typeset -p foo
   typeset -a foo=([1]=([2]=bar) )

   # After
   $ typeset -a foo[1][2]=bar
   $ typeset -p foo
   typeset -a foo=(typeset -a [1]=([2]=bar) )

src/cmd/ksh93/sh/*.c:
- Backport changes from ksh93v- to print 'typeset -a' before sparse
  indexed arrays and properly handle 'typeset -a' in reinput
  commands from 'typeset -p'.

src/cmd/ksh93/tests:
- Add two regression tests to arrays.sh for this change.
- Update the existing regression tests for compatibility with the
  new printed typeset output.

src/cmd/ksh93/include/shlex.h

@@ -90,6 +90,7 @@ typedef struct  _shlex_
 	char		noreserv;	/* reserved works not legal */
 	int		inlineno;	/* saved value of sh.inlineno */
 	int		firstline;	/* saved value of sh.st.firstline */
+	int		assignlevel;	/* nesting level for assignment */
 #if SHOPT_KIA
 	Sfio_t		*kiafile;	/* kia output file */
 	Sfio_t		*kiatmp;	/* kia reference file */