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/enum.sh

@@ -57,7 +57,7 @@ done
 typeset -T X_t=( typeset name=aha )
 typeset -a[X_t] arr
 ) 2> /dev/null
-[[ $? == 1 ]] || err_exit 'typeset -a[X_t] should generate an error message when X-t is not an enumeration type'
+[[ $? == 1 ]] || err_exit 'typeset -a[X_t] should generate an error message when X_t is not an enumeration type'
 
 typeset -a [Color_t] arr
 arr[green]=foo
@@ -168,5 +168,27 @@ exp=': trap: is a special shell builtin'
 [[ $got == *"$exp" ]] || err_exit "enum overrides special builtin" \
 	"(expected match of *$(printf %q "$exp"); got $(printf %q "$got"))"
 
+# ======
+# Various tests backported from ksh93v- for enum type arrays.
+enum bool=(false true)
+bool -A a=( [2]=true [4]=false )
+exp=true
+got=${a[2]}
+[[ $got == $exp ]] || err_exit 'associative array assignment failure when using enums' \
+	"(expected $(printf %q "$exp"); got $(printf %q "$got"))"
+exp=2
+got=${#a[@]}
+[[ $got == $exp ]] || err_exit 'bool -A a should only have two elements' \
+	"(expected $(printf %q "$exp"); got $(printf %q "$got"))"
+
+bool -a bia
+(( bia[4]=false ))
+[[ ${bia[3]} ]] && err_exit 'empty index array element should not produce a value'
+(( bia[3] == 0 )) || err_exit 'empty index array element should be numerically 0'
+bool -A baa
+(( baa[4]=false ))
+[[ ${baa[3]} ]] && err_exit 'empty associative array element should not produce a value'
+(( baa[3] == 0 )) || err_exit 'empty associative array element should be numerically 0'
+
 # ======
 exit $((Errors<125?Errors:125))