Backport ksh93v- regression tests and fix various regression test bugs (#472)

- tests/*.sh: Backported many additional regression tests and test
  fixes from the alpha and beta releases of ksh93v-.

- tests/alias.sh: Avoid trying to add vi to the hash table, as some
  platforms do not provide a vi(1) implementation installed as part
  of the default system. This fixes a regression test failure I was
  getting in one of my Linux virtual machines.

- tests/builtins.sh: Fixed a bug in one of the regression tests that
  caused an incorrect total error count if any of the tests failed.

- tests/sh_match.sh: Fixed a regression test failure on DragonFly
  BSD caused by the diff command printing an extra 'No differences
  encountered' line.

src/cmd/ksh93/tests/attributes.sh

@@ -737,5 +737,18 @@ got=$(env | grep '^\.foo[.=]')
 unset .foo.bar .foo
 set +o allexport
 
+# ======
+# Regression test from ksh93v- 2012-10-24 for testing the zerofill width
+# after exporting a variable.
+unset exp got
+typeset -Z4 VAR1
+VAR1=1
+exp=$(typeset -p VAR1)
+export VAR1
+got=$(typeset -p VAR1)
+got=${got/ -x/}
+[[ $got == "$exp" ]] || err_exit 'typeset -x causes zerofill width to change' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))