Three fixes that together resolve the problem of compiling the XML

Three fixes that together resolve the problem of compiling the XML
parser.  (1) FOR-EACH-CALLEE! claimed to examine all of the callees,
but it wasn't looking at procedures called from descendant blocks that
had been disowned.  (2) When removing dependent constraints, due to
closure, constraints that had indirect dependencies on the now-closed
procedure weren't being removed.  (3) When adding undrifting
constraints due to closure contagion, it's wrong to constrain the
invocation block of a trivial closure.