Fix random_graph() not to generate dead states.
This is actually the third time I fix random_graph(). On 2007-02-06 I changed the function not to generated dead states, but in a way that made it non-deterministic. On 2010-01-20 I made the function deterministic again, but it started to generate dead states as a side effect. This time, I'm making sure that dead states won't come again with a test-case that we should have had from the beginning. * src/tgbaalgos/randomgraph.cc (random_graph): Add an extra indirection array, state_randomizer, so that we can reorder states indices after a random selection without actually changing the value of the indices used by unreachable_states and nodes_to_process. * src/tgbatest/randtgba.test: New file. * src/tgbatest/Makefile.am: Add randtgba.test.