Documentation: move quieting params into manpage-base.xsl

Documentation: move quieting params into manpage-base.xsl

Move a couple of XSL parameters that act to silence
informational/warning messages generated when running xmlto from
manpage-1.72.xsl to manpage-base.xsl.

Since unused parameters are silently ignored, there is no problem
if some version of docbook-xsl does not know about these
parameters. The only problem might be if a version of docbook-xsl
uses the parameters for alternate functionality. Since both
parameters have fairly specific names such a situation is
unlikely.

Testing done with asciidoc 8.3.1 and docbook-xsl 1.74.0.

Signed-off-by: Chris Johnsen <chris_johnsen@pobox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>