NDEBUG-like macro

[Jeffrey A Law]

  In message <Pine.SOL.3.90.980416103727.7938C-100000@hutch.informatik.rwth-aac
hen.de>you write:
  > The tree and rtl structures are terribly overloaded.
Very true.  Though believe it or not it's a lot better than it used
to be, particularly in the tree structure.

Probably the best thing to come out of the attempt to combine static
variables into a "static block" to reduce address computations was
the cleanups we did to the tree structures.

Due to lameness in obstacks and a need to preserve existing semantics
we had to do a recursive copy of the entire tree structure starting
at each node representing a deferred static variable.

This (of course) sucked up a ton of memory, but it also exposed
things like storing ints into pointers, dangling memory references,
storing rtl in tree nodes, etc etc.    I didn't know much about
trees and how to interpret them before I started -- that all changed
by the end of that project! :-)

jeff