Add instructions for building clang while building llvm.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@46881 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/www/get_started.html b/www/get_started.html
index 47909ab..5576bc4 100644
--- a/www/get_started.html
+++ b/www/get_started.html
@@ -100,6 +100,18 @@
   </ul>
 </ol>
 
+<h3>Building clang while building llvm:</h3>
+   <p>Since you've checked out clang into the llvm source tree you can
+   build them all at once with a simple Makefile change. This moves
+   Step 1 above to Step 4.</p>
+  <ul>
+    <li><tt>cd llvm/tools</tt></li>
+    <li>then edit <tt>Makefile</tt> to have a clang target in <tt>PARALLEL_DIRS</tt>
+        just like <tt>llvm-config</tt></li>
+    <li>then just build llvm normally as above and clang will build at
+        the same time</li>
+  </ul>
+
 <p>Note that the C front-end uses LLVM, but does not depend on
   llvm-gcc.  If you encounter problems with building clang, make
   sure you have the latest SVN version of LLVM.  LLVM contains