Trivial: whitespace fixes.
Trivial: prefer C-style comments in .dot output.

C- and C++-style comments are considered first-class comments in the dot language. Graphviz also happens to ignore lines that start with '#', but it's better to use C- or C++-style comments.
Fix failing automata tests.

Now that I have a version of LLVM that supports the 'CHECK-DAG' directive, fix the tests that were failing on Jenkins but not locally.