[rygel] doc: Fix build with --disable-valadoc

[Jens Georg <jensgeorg src gnome org>]

commit eb43699b88d9ba5caab7fd393fbe6bf70bd83d16
Author: Jens Georg <jensg openismus com>
Date:   Sat Dec 1 13:57:04 2012 +0100

    doc: Fix build with --disable-valadoc

 doc/reference/doc-build.am |   14 ++++++++++----
 1 files changed, 10 insertions(+), 4 deletions(-)
---
diff --git a/doc/reference/doc-build.am b/doc/reference/doc-build.am
index 48c9855..85defa2 100644
--- a/doc/reference/doc-build.am
+++ b/doc/reference/doc-build.am
@@ -57,16 +57,22 @@ clean-local:
 
 all: valadoc-gen gtkdoc-gen
 
-endif
-
-RYGEL_GTKDOC_INSTALL_DIR = $(DESTDIR)$(datadir)/gtk-doc/html/lib$(RYGEL_DOCBUILD_MODULE)
-
 # The chmod corrects the directory permissions so that distcheck can remove the installed files.
 install-data-hook: gtkdoc/html/index.html
 	$(MKDIR_P) $(RYGEL_GTKDOC_INSTALL_DIR)
 	cp -d -R $(srcdir)/gtkdoc/html $(RYGEL_GTKDOC_INSTALL_DIR)
 	chmod -R u+w $(RYGEL_GTKDOC_INSTALL_DIR)
 
+else
+install-data-hook:
+	test -d $(srcdir)/gtkdoc/html && $(MKDIR_P) $(RYGEL_GTKDOC_INSTALL_DIR); true
+	test -d $(srcdir)/gtkdoc/html && cp -d -R $(srcdir)/gtkdoc/html $(RYGEL_GTKDOC_INSTALL_DIR); true
+	test -d $(srcdir)/gtkdoc/html && chmod -R u+w $(RYGEL_GTKDOC_INSTALL_DIR); true
+
+endif
+
+RYGEL_GTKDOC_INSTALL_DIR = $(DESTDIR)$(datadir)/gtk-doc/html/lib$(RYGEL_DOCBUILD_MODULE)
+
 uninstall-hook:
 	rm -rf $(RYGEL_GTKDOC_INSTALL_DIR)