aga,agar: New shortcut1 sample graph and testcases based on it

aga,agar: New shortcut1 sample graph and testcases based on it

For all the existing test graphs, the shortest path by cost is also the
shortest path by number of edges.  This patch adds a new test graph where
that is not the case, in order to test that the Dijkstra's algorithm
implementation correctly handles that case.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>