examples: fix handling of syntax errors

The shell grammar does not allow empty statements in then/else part of
an if, but examples/test failed to catch the syntax errors from the
script it ran.  So exited with success anyway.

You would expect 'set -e' to suffice, but with bash 3.2 actually it
does not.  As a matter of fact, I could find a way to have this behave
properly:

    $ cat test.sh
    set -e
    cleanup ()
    {
      status=$?
      echo "cleanup: $status"
      exit $status
    }
    trap cleanup 0 1 2 13 15
    . $1
    s=$?
    echo "test.sh: $s"
    exit $s

    $ cat bistro.test
    if true; then
    fi

    $ /bin/sh ./test.sh ./bistro.test
    ./bistro.test: line 2: syntax error near unexpected token `fi'
    cleanup: 0
    $ echo $?
    0

Remove the set -e (or the trap), and tada, it works...  So we have to
deal with the error by hand.

* examples/test ($exit): Replace with...
($status): this.
Preserve the exit status of the test case.
* examples/c/bistromathic/bistromathic.test: Fix syntax error.

examples/test

@@ -25,7 +25,7 @@ medir=$(dirname "$1" | sed -e 's,.*examples/,,')
 number=1
 
 # Exit status of this script.
-exit=true
+status=0
 
 # top_builddir.
 cwd=$(pwd)
@@ -141,20 +141,20 @@ run ()
       sed -e 's/^/  /' eff
       echo "$me: diff:"
       diff -u exp eff | sed -e 's/^/  /'
-      exit=false
+      status=1
     fi
   else
     echo "$me: FAIL: $number (expected status: $sta_exp, effective: $sta_eff)"
     cat err_eff
-    exit=false
+    status=1
   fi
   number=$(expr $number + 1)
 }
 
 # We have cd'd one level deeper.
 case $1 in
-  /*) . "$1";;
-  *)  . "../$1";;
+  /*) . "$1" || status=2;;
+  *)  . "../$1" || status=2;;
 esac
 
-$exit
+exit $status