include a downscaled png version of the logo when building the html version of the manual


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@10263 a1c6a512-1295-4272-9138-f99709370657
diff --git a/manual/frontpage/frontpage.tex b/manual/frontpage/frontpage.tex
index ae595ae..f223159 100644
--- a/manual/frontpage/frontpage.tex
+++ b/manual/frontpage/frontpage.tex
@@ -1,7 +1,8 @@
 \thispagestyle{empty}
 \vspace*{0.3cm}
 \begin{center}
-\includegraphics[width=10cm]{frontpage/rockboxlogo3.pdf}\\
+\ifpdfoutput{\includegraphics[width=10cm]{frontpage/rockboxlogo3.pdf}}
+{\includegraphics{frontpage/rockbox-web.png}}\\
 \vspace{2cm}
 \huge{The Rockbox Manual\\for\\\playername}\vspace{1cm}\\