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/options.sh

@@ -2,7 +2,7 @@
 #                                                                      #
 #               This software is part of the ast package               #
 #          Copyright (c) 1982-2012 AT&T Intellectual Property          #
-#          Copyright (c) 2020-2021 Contributors to ksh 93u+m           #
+#          Copyright (c) 2020-2022 Contributors to ksh 93u+m           #
 #                      and is licensed under the                       #
 #                 Eclipse Public License, Version 1.0                  #
 #                    by AT&T Intellectual Property                     #
@@ -573,5 +573,37 @@ got=$("$SHELL" -o pipefail -c 'trap "print ERR\ trap" ERR; true | exit 3 | false
 let "(e=$?)==1" && [[ $got == 'ERR trap' ]] || err_exit 'ERR trap + pipefail failed' \
 	"(expected status 1, 'ERR trap'; got status $e, $(printf %q "$got"))"
 
+# ======
+# Basic test for 'ksh -v' backported from ksh93v- 2013-09-13
+exp=:
+got=$("$SHELL" -vc : 2>&1)
+[[ $exp == $got ]] || err_exit 'incorrect output with ksh -v' \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
+# ======
+# Tests that set -m puts background jobs in a separate process group.
+LINENO=$LINENO "$SHELL" -m <<- \EOF
+	. "${SHTESTS_COMMON:-${0%/*}/_common}"
+	[[ $- == *m* ]] || err_exit '$- does not contain m when monitor mode specified'
+	float t=SECONDS
+	sleep 2 & pid=$!
+	kill -KILL -$pid 2> /dev/null || err_exit 'kill to background group failed'
+	wait 2> /dev/null
+	(( (SECONDS-t) > 1 )) && err_exit 'kill did not kill background sleep'
+	exit $Errors
+EOF
+((Errors+=$?))
+
+# ======
+# Test for 'set -u' from ksh93v- 2013-04-09
+"$SHELL" 2> /dev/null <<- \EOF && err_exit 'unset variable with set -u on does not terminate script'
+	set -e -u -o pipefail
+	ls | while read file
+	do
+		files[${#files[*]}]=$fil
+	done
+	exit
+EOF
+
 # ======
 exit $((Errors<125?Errors:125))