Codify the use of Apache License 2.0 software.

Subversion (svnlite) has always been Apache-licensed and LLVM
will be as well starting with version 9.0.0.
Note that core@ must still approve imports of new Apache-license
components in the tree as well as license changes to Apache ones.

Thanks to Brooks for the writeup.

Approved by:		    core@
Differential Revision:	    https://reviews.freebsd.org/D19358

en_US.ISO8859-1/htdocs/internal/software-license.xml

@@ -73,6 +73,20 @@
 	</ul>
       </li>
 
+      <li>
+	<p>The Apache License 2.0 is acceptable for use in some cases.
+	  The Core Team must approve the import of new Apache
+	  License licensed components or the change of license of
+	  existing components to the Apache License.</p>
+
+	<p>The following components are currently approved:</p>
+	<ul>
+	  <li>LLVM toolchain and (with LLVM Exceptions) runtime
+	    components.</li>
+	  <li>Subversion and its dependencies</li>
+	</ul>
+      </li>
+
       <li>
 	<p>Historically, the phrase 'All Rights Reserved.' was
 	included in all copyright notices. The BSD releases had it to