package/gqview: update the upstream URL in Config.in

Update the upstream URL in the help text in Config.in. This
addresses the 'Invalid(404)' URL status in the package stats
web page output.

Signed-off-by: Mark Corbin <mark@dibsco.co.uk>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/gqview/Config.in

@@ -4,4 +4,4 @@ config BR2_PACKAGE_GQVIEW
 	help
 	  GQview is an image viewer for Unix operating systems
 
-	  http://prdownloads.sourceforge.net/gqview
+	  http://gqview.sourceforge.net/