Boostbook: Pass through processing instructions.

[SVN r72002]

test/more/tests/misc/processing.gold

@@ -0,0 +1,5 @@
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<book xmlns:xi="http://www.w3.org/2001/XInclude" id="test" lang="en">
+  <title>Test processing instructions</title>
+  <para><?dbtimestamp format="Y-m-d H:M:S"?></para>
+</book>

test/more/tests/misc/processing.xml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+    Copyright 2011 Daniel James.
+
+    Distributed under the Boost Software License, Version 1.0.
+    (See accompanying file LICENSE_1_0.txt or copy at
+    http://www.boost.org/LICENSE_1_0.txt)
+-->
+<!DOCTYPE boostbook PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
+  "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd">
+<boostbook id="test" xmlns:xi="http://www.w3.org/2001/XInclude"
+           last-revision="$Date: 2010-10-30 15:29:27 +0100 (Sat, 30 Oct 2010) $"
+           lang="en">
+  <title>Test processing instructions</title>
+  <para><?dbtimestamp format="Y-m-d H:M:S"?></para>
+</boostbook>
+
+

xsl/docbook.xsl

@@ -382,6 +382,10 @@ Error: XSL template 'link-or-anchor' called with invalid link-type '<xsl:value-o
     </xsl:element>
   </xsl:template>
 
+  <xsl:template match="processing-instruction()">
+    <xsl:copy/>
+  </xsl:template>
+
   <xsl:template match="code">
     <computeroutput>
       <xsl:apply-templates mode="annotation"/>