package/mrouted: add .hash file

Similar to jquery-keyboard, it seems the mrouted tarball on the
autobuilder is corrupt.  Fix it by adding a .hash file so it falls back to
our s.b.o mirror.

Signed-off-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/mrouted/mrouted.hash

@@ -0,0 +1,2 @@
+# Locally calculated
+sha256 181908f7025c5a2dee2e50d86888780469eaa9e1bd42d3eca9dfed8274aecd3d  mrouted-3.9.7.tar.gz