examples: bistromathic: when quitting, close the current line

When the user ctrl-d the line, we left the cursor not at col 0.
Let's fix that.
This revealed a few short-comings in the testing framework.

* examples/test (run): Also display the diffs.
And support -n.
* examples/c/bistromathic/bistromathic.test
* examples/c/bistromathic/parse.y

examples/test

@@ -68,15 +68,21 @@ trap cleanup 0 1 2 13 15
 mkdir $$.dir
 cd $$.dir
 
-# run [-noerr] EXPECTED-EXIT-STATUS EXPECTED-OUTPUT [PARSER-OPTIONS]
-# ------------------------------------------------------------------
+# run [-noerr, -n] EXPECTED-EXIT-STATUS EXPECTED-OUTPUT [PARSER-OPTIONS]
+# ----------------------------------------------------------------------
 # -noerr: ignore stderr, otherwise merge it into effective output.
+# -n: not final end-of-line in expected-output
 run ()
 {
   noerr=false
-  case $1 in
-    (-noerr) noerr=true; shift;;
-  esac
+  echo=echo
+  while true; do
+    case $1 in
+      (-noerr) noerr=true; shift;;
+      (-n)     echo=printf; shift;;
+      (*)      break;;
+    esac
+  done
 
   # Expected exit status.
   sta_exp=$1
@@ -84,9 +90,9 @@ run ()
 
   # Expected output.
   if $strip_prompt; then
-      out_exp=$(echo "$1" | sed -e 's/^> err:/err:/;/^> /d')
+      $echo "$1" | sed -e '/^> /d' >exp
   else
-      out_exp=$1
+      $echo "$1" >exp
   fi
   shift
 
@@ -96,19 +102,21 @@ run ()
   prog "$@" - <input >out_eff 2>err_eff || sta_eff=$?
 
   # Combine effective output and error streams.
-  out_eff=$(cat out_eff && $noerr || sed -e 's/^/err: /g' err_eff)
+  { cat out_eff && $noerr || sed -e 's/^/err: /g' err_eff; } >eff
 
   if test $sta_eff -eq $sta_exp; then
-    if test "$out_eff" = "$out_exp"; then
+    if cmp eff exp 2>/dev/null; then
       echo "$me: PASS: $number"
     else
       echo "$me: FAIL: $number"
       echo "$me: input:"
       sed -e 's/^/  /' input
       echo "$me: expected output:"
-      echo "$out_exp" | sed -e 's/^/  /'
+      sed -e 's/^/  /' exp
       echo "$me: effective output:"
-      echo "$out_eff" | sed -e 's/^/  /'
+      sed -e 's/^/  /' eff
+      echo "$me: diff:"
+      diff -u exp eff | sed -e 's/^/  /'
       exit=false
     fi
   else