Actually create the man/ subdirectories before installing.

documentation/Makefile.in

diff --git a/documentation/Makefile.in b/documentation/Makefile.in
index 0729d34..3c06ee4 100644
--- a/documentation/Makefile.in
+++ b/documentation/Makefile.in
@@ -50,7 +50,8 @@
 	for i in $(INCLUDES); do $(LN_S) $(TOPSRCDIR)/$$i $$i || exit 1; done
 
 install:: 
-	[ -d $(mandir) ] || mkdir -p $(mandir)
+	$(INSTALL) -d $(mandir)/man$(prog_manext)
+	$(INSTALL) -d $(mandir)/man$(conf_manext)
 	$(INSTALL_DATA) wine.man $(mandir)/man$(prog_manext)/wine.$(prog_manext)
 	$(INSTALL_DATA) wine.conf.man $(mandir)/man$(conf_manext)/wine.conf.$(conf_manext)