title: DoxygenLayout.xml parsing not finding explicit link request
body: <p>I am migrating from doxygen 1.8.4 to 1.8.8. My DoxygenLayout.xml file has an entry like this:</p>
  
  <pre><code>&lt;tab type="user" url="@ref FAQ" visible="yes" title="FAQ" intro=""/&gt;
  </code></pre>
  
  <p>In my Doxyfile, my <code>INPUT</code> includes "faq.htm" and I see in the Doxy output:</p>
  
  <pre><code>Reading /git/bfg_iOS_sdk/bfg_internal/docs/htmlFramework/faq.htm...
  </code></pre>
  
  <p>My "faq.htm" file begins like this:</p>
  
  <pre><code>/** 
  \page FAQ Frequently Asked Questions
  \ingroup FAQ
  \{
  </code></pre>
  
  <p>With Doxy 1.8.4, there was no issue. In 1.8.8 I see these warnings:</p>
  
  <pre><code>explicit link request to 'FAQ' in layout file 'DoxygenLayout.xml' could not be resolved
  </code></pre>
  
  <p>What am I doing wrong?</p>
  
  <p><strong>Update</strong></p>
  
  <p>I am (and have been) using these file patterns:</p>
  
  <pre><code>FILE_PATTERNS          = *.m \
                           *.mm \
                           *.html \
                           *.h \
                           *.htm
  </code></pre>
  
  <p>I continue to see these warnings with Doxygen 1.8.10, and my doc set fails to build properly.</p>