tests: fix maintainer-xml-check.

* data/xslt/xml2dot.xsl (xsl:template match="bison-xml-report"):
Update output to include comments now produced by --graph.
(xsl:template match="automaton"): As for --graph, name the
digraph after the grammar file.
* src/print-xml.c (escape_bufs): Enlarge array.
(print_xml): Add bug-report and url attributes to
bison-xml-report element.
(cherry picked from commit bc81de36b7)

data/xslt/xml2dot.xsl

@@ -35,11 +35,27 @@
 </xsl:template>
 
 <xsl:template match="bison-xml-report">
-  <xsl:apply-templates select="automaton"/>
+  <xsl:text>// Generated by GNU Bison </xsl:text>
+  <xsl:value-of select="@version"/>
+  <xsl:text>.&#10;</xsl:text>
+  <xsl:text>// Report bugs to &lt;</xsl:text>
+  <xsl:value-of select="@bug-report"/>
+  <xsl:text>&gt;.&#10;</xsl:text>
+  <xsl:text>// Home page: &lt;</xsl:text>
+  <xsl:value-of select="@url"/>
+  <xsl:text>&gt;.&#10;&#10;</xsl:text>
+  <xsl:apply-templates select="automaton">
+    <xsl:with-param name="filename" select="filename"/>
+  </xsl:apply-templates>
 </xsl:template>
 
 <xsl:template match="automaton">
-  <xsl:text>digraph Automaton {&#10;</xsl:text>
+  <xsl:param name="filename"/>
+  <xsl:text>digraph "</xsl:text>
+  <xsl:call-template name="escape">
+    <xsl:with-param name="subject" select="$filename"/>
+  </xsl:call-template>
+  <xsl:text>"&#10;{&#10;</xsl:text>
   <xsl:apply-templates select="state"/>
   <xsl:text>}&#10;</xsl:text>
 </xsl:template>