but I want to get some stuff checked in. Theoretically, this is
   all enabled only with sac2c option -ssaiv. The intent is to make
   that option go away, and to make flattened code the standard for
   all code in the above phases.

2. -d treecheck code to detect non-flattened GENERATOR_BOUND1 and
   GENERATOR_BOUND2, which are the only ones I absolutely need to
   be flattened, at present.