revert(3p/git): Revert merge of git upstream at v2.26.2

This causes cgit to serve error pages, which is undesirable.

This reverts commit 5229c9b232, reversing
changes made to f2b211131f.

third_party/git/Documentation/manpage-bold-literal.xsl

@@ -1,13 +1,12 @@
 <!-- manpage-bold-literal.xsl:
      special formatting for manpages rendered from asciidoc+docbook -->
 <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
-		xmlns:d="http://docbook.org/ns/docbook"
 		version="1.0">
 
 <!-- render literal text as bold (instead of plain or monospace);
      this makes literal text easier to distinguish in manpages
      viewed on a tty -->
-<xsl:template match="literal|d:literal">
+<xsl:template match="literal">
 	<xsl:value-of select="$git.docbook.backslash"/>
 	<xsl:text>fB</xsl:text>
 	<xsl:apply-templates/>