Various cleanups, mostly in regression tests

src/cmd/ksh93/data/variables.sh: shtab_variables[]:
- Remove unused "CSWIDTH" entry. All use of it (including the
  matching CSWIDTHNOD macro) was removed in version 2003-04-22.

src/cmd/ksh93/tests/variables.sh:
- For the tests on the shtab_variables[] variables, read the
  variable names straight from variables.c instead of synching
  the list in the test script, which would surely be forgotten.

src/cmd/ksh93/tests/*.sh:
- Fix a number of mistaken tries to count errors from a subshell.
- Fix miscellaneous minor breakage and typos.

src/cmd/ksh93/tests/grep.sh

@@ -85,11 +85,12 @@ and some lines contain bar only.
 However, many lines contain both foo and also bar.
 A line containing foobar should also be counted.
 There should be six lines with foo and bar.
-There are only two line with out foo but with bar.
+There are only two lines without foo but with bar.
 !
 
-if	(( $(grep -c 'foo*bar' $tmp/grep ) != 6))
-then	err_exit
+got=$(grep -c 'foo*bar' $tmp/grep 2>&1)
+if	[[ $got != 6 ]]
+then	err_exit "shell version of grep fails (expected 6, got $(printf %q "$got"))"
 fi
 
 exit $((Errors<125?Errors:125))