Add Hurd to OS list and disable dv1394 in the Hurd case.
patch by Andres Mejia, mcitadel gmail com

backport r18938 by diego


Originally committed as revision 22237 to svn://svn.ffmpeg.org/ffmpeg/branches/0.5
diff --git a/configure b/configure
index e96db9e..ee5a2a5 100755
--- a/configure
+++ b/configure
@@ -1659,6 +1659,9 @@
         ;;
     gnu/kfreebsd)
         ;;
+    gnu)
+        disable dv1394
+        ;;
 
     *)
         die "Unknown OS '$target_os'."