Resort back to using GNU sed in .sh built manpages, as we only need them at 'make dist' time now; doesn't matter that BSD can't run them

termkey_waitkey.3.sh

@@ -29,7 +29,9 @@ No key events are ready and the terminal has been closed, so no more will arrive
 The following example program prints details of every keypress until the user presses "Ctrl-C".
 .PP
 .in +4n
-`while read LINE; do echo ".br"; echo "$LINE"; done <demo.c`
+EOF
+sed i.br demo.c
+cat <<EOF
 .in
 .nf
 .fi