This is primarily cleanup, but there are 2 functional changes included:
- It used to accidentally reorder bodies of AstNodeIf that were outside
an AstAlways. Now it will not touch anything outside an AstAlways.
- Removed one redundant edge from the graph which perturbs the result of
V3Graph::acyclic. This should make no difference for the actual
intended result of reordering NBAs to eliminate shadow variables.