Test for rsvg-convert in configure.ac

If it's not present, we just don't install the icon.

configure.ac

@@ -30,6 +30,8 @@ PKG_CHECK_MODULES(POPPLER, [poppler-glib gdk-2.0 gio-2.0],
 			   [have_poppler=yes], [have_poppler=no])
 AM_CONDITIONAL(HAVE_POPPLER, test "x$have_poppler" = "xyes")
 
+AC_CHECK_PROG(RSVG_CONVERT, rsvg-convert, rsvg-convert)
+AM_CONDITIONAL(HAVE_RSVG_CONVERT, test -n "$RSVG_CONVERT")
 
 AC_ARG_ENABLE(x11-compositor, [  --enable-x11-compositor],,
 	      enable_x11_compositor=yes)

data/Makefile.am

@@ -20,7 +20,11 @@ dist_waylanddata_DATA =				\
 	top_side.png				\
 	xterm.png				\
 	wayland.svg				\
-	wayland.png
+	$(wayland_icon_png)
+
+if HAVE_RSVG_CONVERT
+wayland_icon_png = wayland.png
 
 wayland.png : wayland.svg
-	rsvg-convert -w 128 -h 128 wayland.svg -o wayland.png
+	$(RSVG_CONVERT) -w 128 -h 128 wayland.svg -o wayland.png
+endif