add hack-a-round for language specified markdown code blocks

When language is specified in a markdown code block such as:

````
```c
    printf("Hello, world!\n");
```
````

is used, the resulting HTML as produced by `pandoc(1)` combined
with our revised `ioccc.css` is not intent the code block well.

A temporary "_hack-a-round_" is to turn the "markdown code language
specifier" into an HTML comment.  For example:

````
```<!---c-->
    printf("Hello, world!\n");
```
````

This commits turns off existing markdown code language specifiers
for now, while preserving our ability to restore them in the future
when a better  "_hack-a-round_" to the "markdown code language
specifier" problem is found.

The HTML impact if this "_hack-a-round_" is to produce HTML that
looks like this:

```
<pre class="&lt;!---c--&gt;"><code> .. </code></pre>
```

We might be able to create a complex set of classes for each markdown
code language (there won't be very many) in `ioccc.css`, or we might
find a more general CSS (or maybe `pandoc(1)`?) solution.

For now, this hack-a-round will have to do.

1989/jar.1/index.html

@@ -142,22 +142,22 @@ Location: <a href="../../location.html#SE">SE</a> - <em>Kingdom of Sweden</em> (
 
 <h2 id="to-build">To build:</h2>
 <p>NOTE: this will run the program itself.</p>
-<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">make</span> clobber all</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make clobber all</code></pre>
 <p>There is an alternate version with a slight difference that you may wish to try.
 See the <a href="#alternate-code">Alternate code</a> section below for more details.</p>
 <h2 id="to-use">To use:</h2>
-<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./jar.1</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./jar.1</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
 <p>This alternate code, which prints something slightly different, is provided as well.</p>
 <h3 id="alternate-build">Alternate build:</h3>
 <p>NOTE: this will run the program itself.</p>
-<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">make</span> clobber alt</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make clobber alt</code></pre>
 <h3 id="alternate-use">Alternate use:</h3>
-<div class="sourceCode" id="cb4"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>    <span class="ex">./jar.1.alt</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./jar.1.alt</code></pre>
 <h2 id="judges-remarks">Judges’ remarks:</h2>
 <p>On many systems the compiler will not allow you to send the object file to
 <code>/dev/tty</code>. The author suggested:</p>
-<div class="sourceCode" id="cb5"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">cc</span> <span class="at">-c</span> <span class="at">-o</span> /dev/tty jar.1.c</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    cc -c -o /dev/tty jar.1.c</code></pre>
 <p>As a last resort the <code>jar.1.sh</code> script provided simulates
 writing the raw binary of the .o file to the terminal.</p>
 <p>Abuse of the rules winning entry usually result in a change of the rules.