- Signals the state of the dominator infomation.
- Values: dom_none, dom_consistent, dom_inconsistent
- dom_none: doms are not computed, no memory is allocated. The access routines
- may not be used.
- dom_consistent: dominator information is computed and correct,
- dom_inconsistent: dominator information is computed, memory is still allocated,
- but the graph has been changed since. Using the access routines is possible,
- obtained information may be incorrect. */