Add FAQ 4.6 - about changes to main() args

As numerous entries had to have arg type or arg count in main() changed
(usually to do with clang but not always) it seems like this should be
added to the FAQ.

faq.html

@@ -442,6 +442,7 @@
 other inconsistencies with the original entry?</a></li>
 <li><a href="#faq4_4">4.4 - What is the meaning of the file ending in .orig.c in IOCCC entries?</a></li>
 <li><a href="#faq4_5">4.5 - Why were alternate versions added to some entries when the original entry worked fine and well?</a></li>
+<li><a href="#faq4_6">4.6 - Why was arg count and/or type changed in main() in some older entries?</a></li>
 </ul>
 <h2 id="section-5---helping-the-ioccc">Section 5 - <a href="#faq5">Helping the IOCCC</a></h2>
 <ul>
@@ -2019,6 +2020,21 @@ prevented the entry from working properly and it seemed like it should be added
 as well, for fun.</p>
 <p>In some cases it might be better to not have them but as noted this is a
 judgement call.</p>
+<div id="faq4_6">
+<h3 id="faq-4.6-why-was-arg-count-andor-type-changed-in-main-in-some-older-entries">FAQ 4.6: Why was arg count and/or type changed in main() in some older entries?</h3>
+</div>
+<p>There are a number of reasons this was done but they usually come down to a
+mis-feature or defect in the <code>clang</code> compiler.</p>
+<p>In all versions of <code>clang</code> the first arg must be an <code>int</code> and the rest must be a
+<code>char **</code> but in some versions it also objects to the number of args in
+<code>main()</code>. In the versions observed that complain about the number of args it
+says that there must be 0, 2 or 3 args. This only was triggered with 4 args, not
+1, but to future proof the entry entries that had only one arg to <code>main()</code> were
+changed to two.</p>
+<p>The above also meant that some entries that were recursive calls to <code>main()</code>
+could no longer be so: <code>main()</code> instead had to call another function that has
+the body of the old <code>main()</code> and that function would call itself again. In some
+cases, however, this had to be done even without <code>clang</code> objections.</p>
 <div id="faq5">
 <h2 id="section-5-updating-or-correcting-ioccc-web-site-content">Section 5: Updating or correcting IOCCC web site content</h2>
 </div>