[PATCH] do not refresh ratpoison.man.1 with --disable-maintainer-mode

To avoid files shipped in the tarball to be regenerated with
--disable-maintainer-mode, add the magic marker so that in that case
there are no prerequisites, so the file is never regenerated.

---
 doc/Makefile.am | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/doc/Makefile.am b/doc/Makefile.am
index 1b8da1c..fbb5165 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -31,7 +31,7 @@ ratpoison.1: $(srcdir)/ratpoison.$(manpage_format).1 Makefile
 	chmod 0644 "$$tmp" && \
 	mv "$$tmp" ratpoison.1
 
-$(srcdir)/ratpoison.man.1: $(srcdir)/ratpoison.mdoc.1
+$(srcdir)/ratpoison.man.1: @MAINTAINER_MODE_TRUE@ $(srcdir)/ratpoison.mdoc.1
 	tmp=`mktemp` && \
 	$(MANDOC) -Tman < $(srcdir)/ratpoison.mdoc.1 > "$$tmp" && \
 	chmod 0644 "$$tmp" && \