Add asciidoctor extension to better format the manpage

Signed-off-by: Jean-Noël Avila <jn.avila@free.fr>

asciidoctor-extensions.rb

+require 'asciidoctor'
+require 'asciidoctor/extensions'
+
+module Git
+  module Documentation
+    class LinkGitProcessor < Asciidoctor::Extensions::InlineMacroProcessor
+      use_dsl
+
+      named :chrome
+
+      def process(parent, target, attrs)
+        prefix = parent.document.attr('git-relative-html-prefix')
+        if parent.document.doctype == 'book'
+          "<ulink url=\"#{prefix}#{target}.html\">" \
+          "#{target}(#{attrs[1]})</ulink>"
+        elsif parent.document.basebackend? 'html'
+          %(<a href="#{prefix}#{target}.html">#{target}(#{attrs[1]})</a>)
+        elsif parent.document.basebackend? 'manpage'
+          "#{target}(#{attrs[1]})"
+	end
+      end
+    end
+  end
+end
+
+Asciidoctor::Extensions.register do
+  inline_macro Git::Documentation::LinkGitProcessor, :linkgit
+end

makefile.locale

@@ -22,7 +22,7 @@ include ../../Makefile
 
 XMLTO_EXTRA += --searchpath ../..
 ifdef USE_ASCIIDOCTOR
-ASCIIDOC_EXTRA += -I../..
+ASCIIDOC_EXTRA += -I../.. -I. -rasciidoctor-extensions
 else
 ASCIIDOC_CONF = -f ../../asciidoc.conf
 endif
@@ -43,12 +43,17 @@ ifndef V
 	QUIET_ASCIIDOC	= @echo '   ' ASCIIDOC $(lang) $@;
 endif
 
+-include ../GIT-VERSION-FILE
+
 $(HTML_FILTER): %.html: %.txt
-	$(QUIET_ASCIIDOC)asciidoctor -b xhtml5 -d manpage $<
+	$(QUIET_ASCIIDOC)asciidoctor -b xhtml5 -d manpage -d manpage -I.. -I. -rasciidoctor-extensions \
+        -amanversion=$(GIT_VERSION) -amanmanual='Git Manual' -amansource='Git  $(GIT_VERSION)' $<
 
 MANPAGES=$(patsubst %.txt,%.1,$(MAN_FILTER))
 $(MANPAGES): %.1: %.txt
-	$(QUIET_ASCIIDOC)asciidoctor -b manpage -d manpage -o $@ $<
+	$(QUIET_ASCIIDOC)asciidoctor -b manpage -d manpage -o $@ \
+        -I. -I.. -rasciidoctor-extensions \
+        -amanmanual='Git Manual' -amansource='Git $(GIT_VERSION)' $<
 
 man: $(MANPAGES)
 html: $(HTML_FILTER)