[wwwdocs, patch] Add libgccjit to gcc-5/changes.html

[David Malcolm <dmalcolm at redhat dot com>]

This patch adds an <h2>-level section about libgccjit between the
sections on languages and targets.

It has various links to the documentation (now that that's on the
website), and to a couple of 3rd party repos (the Python and D
bindings).  It also mentions the license of the library.

OK to commit?

Dave

Index: htdocs/gcc-5/changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v
retrieving revision 1.78
diff -u -p -r1.78 changes.html
--- htdocs/gcc-5/changes.html	5 Feb 2015 13:52:05 -0000	1.78
+++ htdocs/gcc-5/changes.html	6 Feb 2015 02:46:57 -0000
@@ -451,6 +451,33 @@ void operator delete[] (void *, std::siz
 <!-- h3 id="go">Go</h3 -->
 <!--h3 id="java">Java (GCJ)</h3-->
 
+<h2 id="jit">libgccjit</h2>
+<p>New in GCC 5 is the ability to build gcc as a shared library for embedding
+in other processes (such as interpreters), suitable for Just-In-Time
+compilation to machine code.</p>
+
+<p>The shared library has a <a href="https://gcc.gnu.org/onlinedocs/jit/intro/index.html";>C API</a>
+and a
+<a href="https://gcc.gnu.org/onlinedocs/jit/cp/index.html";>C++ wrapper API</a>
+providing some "syntactic sugar".
+There are also bindings available from 3rd parties for
+<a href="https://github.com/davidmalcolm/pygccjit";>Python</a> and for
+<a href="https://github.com/ibuclaw/gccjitd";>D</a>.</p>
+
+<p>For example, this library can be used by interpreters for
+<a href="https://gcc.gnu.org/onlinedocs/jit/intro/tutorial04.html";>compiling
+functions from bytecode to machine code</a>.</p>
+
+<p>The library can also be used for ahead-of-time compilation, enabling
+GCC to be plugged into a pre-existing frontend.  An example of using
+this to build a compiler for an esoteric language we'll refer to as "brainf"
+can be seen <a href="https://gcc.gnu.org/onlinedocs/jit/intro/tutorial05.html";>
+here</a>.</p>
+
+<p>libgccjit is licensed under the GPLv3 (or at your option, any later version)</p>
+
+<p>It should be regarded as experimental at this time.</p>
+
 <h2 id="targets">New Targets and Target Specific Improvements</h2>
 
 <h3 id="aarch64">AArch64</h3>