Fix a few minor issues (#473)

Changes:
- Fixed two xtrace test failures introduced in commit cfc8744c.
- The definition of _use_ntfork_tcpgrp in xec.c is now dependent on
  SHOPT_SPAWN being defined (re: 8e9ed5be).
- Removed many unnecessary newlines and fixed various typos.

src/cmd/ksh93/tests/subshell.sh

@@ -1137,7 +1137,7 @@ fun()
 	print -n stdout=$foo
 	print -u2 stderr=$foo
 }
-[[ `fun 2>&1` == 'stdout=foostderr=foo' ]] || err_exit 'nested command substitution with 2>&1 not working'
+[[ `set +x; fun 2>&1` == 'stdout=foostderr=foo' ]] || err_exit 'nested command substitution with 2>&1 not working'
 
 # Various regression tests from ksh93v- 2012-10-04 and 2012-10-24
 $SHELL > /dev/null -c 'echo $(for x in whatever; do case y in *) true;; esac; done)' || err_exit 'syntax error with case in command substitution'

src/cmd/ksh93/tests/types.sh

@@ -725,7 +725,7 @@ exp=$'start1\ntypeset -x a=one\nstart2\ntypeset -x a=one\nend2\nend1'
 
 # Backported regression test from ksh93v- 2013-08-07 for
 # short integer arrays in types.
-got=$("$SHELL" 2>&1 <<- \EOF
+got=$(set +x; "$SHELL" 2>&1 <<- \EOF
        typeset -T X_t=(typeset -si -a arr=(7 8) )
        X_t x
        print -r -- $((x.arr[1]))