Make man page building quiet when DOCBOOK_XSL_172 is defined

Tell xmlto to repress printing of the lines:

	Note: meta date   : No date. Using generated date       git-xyx
	Note: Writing git-xyz.1

Signed-off-by: Jonas Fonseca <fonseca@diku.dk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/manpage-1.72.xsl

@@ -1,5 +1,9 @@
-<!-- callout.xsl: converts asciidoc callouts to man page format -->
+<!-- Based on callouts.xsl. Fixes man page callouts for DocBook 1.72 XSL -->
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+
+<xsl:param name="man.output.quietly" select="1"/>
+<xsl:param name="refentry.meta.get.quietly" select="1"/>
+
 <xsl:template match="co">
 	<xsl:value-of select="concat('&#x2593;fB(',substring-after(@id,'-'),')&#x2593;fR')"/>
 </xsl:template>