[www] Remove stale text about default c++ standard from cxx_status.html

[russell.gallop]

Summary

Since r320250 c++98 is no longer the default, but cxx_status.html still said it was. I think the original intent of the statement was to say that clang by default supports some c++11 features which is no longer as pertinent information so this patch removes this statement. The page no longer mentions the default c++ dialect.

An alternative would be to say the default prior to Clang 6.0 (gnu++98) and from 6.0 onwards (gnu++14).

[russell.gallop]

Ping. Is this okay to land, or have I missed something? Thanks.

[russell.gallop]

Latest page looks fine: https://clang.llvm.org/cxx_status.html#cxx11

clang/www/cxx_status.html

<p>Clang implements all of the ISO C++ 1998 standard
   except for <tt>export</tt> (which was removed in C++11).
 
 <h2 id="cxx11">C++11 implementation status</h2>
 
 <p>Clang 3.3 and later implement all of the <a
   href="https://www.iso.org/standard/50372.html">ISO
   C++ 2011 standard</a>.
 
-<p>By default, Clang builds C++ code according to the C++98 standard, with many
-C++11 features accepted as extensions. You can use Clang in C++11 mode with the
-<code>-std=c++11</code> option. Clang's C++11 mode can be used
-with <a href="https://libcxx.llvm.org/">libc++</a> or with gcc's libstdc++.
+<p>You can use Clang in C++11 mode with the <code>-std=c++11</code> option.
+Clang's C++11 mode can be used with <a
+href="https://libcxx.llvm.org/">libc++</a> or with gcc's libstdc++.
 
 <details>
 <summary>List of features and minimum Clang version with support</summary>
 
 <table width="689" border="1" cellspacing="0">
  <tr>
     <th>Language Feature</th>
     <th>C++11 Proposal</th>