Make the asciidoc build process work from outside top_srcdir

Edited a little by Sebastian

doc/Makefile.am

@@ -22,7 +22,7 @@ DIST_SUBDIRS = design-paper spec
 # Generate the html documentation from asciidoc, but don't do
 # machine-specific replacements yet
 $(html_in) :
-	$(top_srcdir)/doc/asciidoc-helper.sh html @ASCIIDOC@ @SED@ $@
+	$(top_srcdir)/doc/asciidoc-helper.sh html @ASCIIDOC@ @SED@ $(top_srcdir)/doc/$@
 
 tor.html.in : tor.1.txt
 torify.html.in : torify.1.txt
@@ -32,7 +32,7 @@ tor-resolve.html.in : tor-resolve.1.txt
 # Generate the manpage from asciidoc, but don't do
 # machine-specific replacements yet
 $(man_in) :
-	$(top_srcdir)/doc/asciidoc-helper.sh man @A2X@ @SED@ $@
+	$(top_srcdir)/doc/asciidoc-helper.sh man @A2X@ @SED@ $(top_srcdir)/doc/$@
 
 tor.1.in : tor.1.txt
 torify.1.in : torify.1.txt
@@ -42,6 +42,9 @@ tor-resolve.1.in : tor-resolve.1.txt
 # use ../config.status to swap all machine-specific magic strings
 # in the asciidoc with their replacements.
 $(asciidoc_product) :
+	if test -e $(top_srcdir)/doc/$@.in && ! test -e ./$@.in ; then \
+		cp $(top_srcdir)/doc/$@.in .; \
+	fi
 	../config.status --file=$@;
 
 tor.1 : tor.1.in