Documentation: option to render literal text as bold for manpages

This allows manpages viewed on a tty to render inline literal
text in a manner that is distinct from the surrounding text.

The initial implementation (pre-mailing-list) of this patch
included a conditional variant of the XSLT code in
manpage-base.xsl and use xmlto's --stringparam option to
optionally enable the functionality. It turns out that
--stringparam is broken in all versions of xmlto except for the
pre-release, SVN version. Since xmlto is a shell script the patch
to fix it is simple enough, but I instead opted to use xmlto's
"module" functionality.

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>

Documentation/Makefile

@@ -42,6 +42,7 @@ man7dir=$(mandir)/man7
 ASCIIDOC=asciidoc
 ASCIIDOC_EXTRA =
 MANPAGE_XSL = manpage-normal.xsl
+XMLTO_EXTRA =
 INSTALL?=install
 RM ?= rm -f
 DOC_REF = origin/man
@@ -93,6 +94,9 @@ else
 	ASCIIDOC_EXTRA += -a git-asciidoc-no-roff
 	endif
 endif
+ifdef MAN_BOLD_LITERAL
+XMLTO_EXTRA += -m manpage-bold-literal.xsl
+endif
 
 #
 # Please note that there is a minor bug in asciidoc.
@@ -192,7 +196,7 @@ $(MAN_HTML): %.html : %.txt
 
 %.1 %.5 %.7 : %.xml
 	$(RM) $@
-	xmlto -m $(MANPAGE_XSL) man $<
+	xmlto -m $(MANPAGE_XSL) $(XMLTO_EXTRA) man $<
 
 %.xml : %.txt
 	$(RM) $@+ $@

Documentation/manpage-bold-literal.xsl

@@ -0,0 +1,17 @@
+<!-- manpage-bold-literal.xsl:
+     special formatting for manpages rendered from asciidoc+docbook -->
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+		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">
+	<xsl:value-of select="$git.docbook.backslash"/>
+	<xsl:text>fB</xsl:text>
+	<xsl:apply-templates/>
+	<xsl:value-of select="$git.docbook.backslash"/>
+	<xsl:text>fR</xsl:text>
+</xsl:template>
+
+</xsl:stylesheet>