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.

1988/applin/index.html

@@ -141,18 +141,18 @@ Location: <a href="../../location.html#US">US</a> - <em>United States of America
 <!-- START: this line starts content for HTML phase 21 by: bin/pandoc-wrapper.sh via bin/md2html.sh -->
 
 <h2 id="to-build">To build:</h2>
-<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> all</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make all</code></pre>
 <p>A smaller version, originally called <code>zsmall.c</code> (and still exists as such, as
 the source of the alt code), of <a href="applin.c">applin.c</a>, can be found in
 <a href="applin.alt.c">applin.alt.c</a>. Your machine may have an easier time with this
 program. See the <a href="#alternate-code">Alternate code</a> section below for details.</p>
 <h2 id="try">Try:</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">./applin</span></span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    ./applin</code></pre>
 <h2 id="alternate-code">Alternate code:</h2>
 <p>As noted above a smaller version can be used in case your <code>cpp</code> has a hard time
 with this entry.</p>
 <h3 id="alternate-build">Alternate build:</h3>
-<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> alt</span></code></pre></div>
+<pre class="&lt;!---sh--&gt;"><code>    make alt</code></pre>
 <p>Use <code>applin.alt</code> as you would <code>applin</code> above.</p>
 <h4 id="history-about-the-smaller-version">History about the smaller version:</h4>
 <p>Way back in 1988 ..</p>