[seed] doc: fix make distcheck

[Mathieu Duponchelle <mathieudu src gnome org>]

commit 7daa813d3f00574b8d7222fa7e0aa30e26e43f19
Author: Mathieu Duponchelle <mathieu duponchelle opencreed com>
Date:   Fri Sep 16 01:05:16 2016 +0200

    doc: fix make distcheck
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771510

 doc/modules/Makefile.am   |    2 +-
 doc/reference/Makefile.am |   18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletions(-)
---
diff --git a/doc/modules/Makefile.am b/doc/modules/Makefile.am
index 1f3ee15..3f4b44d 100644
--- a/doc/modules/Makefile.am
+++ b/doc/modules/Makefile.am
@@ -4,7 +4,7 @@ EXTRA_DIST=make-functions.js book.xml version.xml.in
 if ENABLE_GTK_DOC
 html/index.html: version.xml book.xml sqlite/sqlite.xml sqlite/sqlite-funcs.xml readline/readline.xml 
readline/readline-funcs.xml make-functions.js gtkbuilder/gtkbuilder-funcs.xml gtkbuilder/gtkbuilder.xml 
sandbox/sandbox.xml sandbox/sandbox-funcs.xml
        mkdir -p html;
-       gtkdoc-mkhtml "Seed" book.xml;
+       gtkdoc-mkhtml --path="$(abs_builddir)" "Seed" $(srcdir)/book.xml;
        mv *.html *.css *.png *.sgml *.devhelp* html
 
 bookdir = $(docdir)/modules/html
diff --git a/doc/reference/Makefile.am b/doc/reference/Makefile.am
index b5c6595..c3e429d 100644
--- a/doc/reference/Makefile.am
+++ b/doc/reference/Makefile.am
@@ -39,6 +39,24 @@ MKTMPL_OPTIONS=
 # e.g. FIXXREF_OPTIONS=--extra-dir=../gdk-pixbuf/html --extra-dir=../gdk/html
 FIXXREF_OPTIONS=
 
+extra_paths = \
+       $(abs_builddir) \
+       $(abs_top_srcdir)/doc/modules/readline \
+       $(abs_top_builddir)/doc/modules/readline \
+       $(abs_top_srcdir)/doc/modules/sqlite \
+       $(abs_top_builddir)/doc/modules/sqlite \
+       $(abs_top_srcdir)/doc/modules/gtkbuilder \
+       $(abs_top_builddir)/doc/modules/gtkbuilder \
+       $(abs_top_srcdir)/doc/modules/sandbox \
+       $(abs_top_builddir)/doc/modules/sandbox \
+       $(NULL)
+
+
+space = $(NULL) $(NULL)
+
+# Add the builddirs to the HTML path so that built files are found
+MKHTML_OPTIONS=--path=$(subst $(space),:,$(extra_paths))
+
 # Used for dependencies. The docs will be rebuilt if any of these change.
 # e.g. HFILE_GLOB=$(top_srcdir)/gtk/*.h
 # e.g. CFILE_GLOB=$(top_srcdir)/gtk/*.c