Reverse some recent, erroneous changes in .cvsignore handling.

Some randomness is leaking in from the envoronment.  The twotag egression
test succeeds when run from inside Emacs, but not when run from the shell!
All other tests succeed in both environments.
Demonstrate the order instability problem with "make breakit".

Order in which commits are dumped is different depending on whether
run in shell or emacs.  Instrumentation conditioned on ORDERDEBUG
and ORDERDEBUG2.
Adapt some of Keith's conditioned-out code to attack the instability.

Alas, dump_rev_tree() turns out not to be very useful  dump_rev_list()
coredumps, doubtless due to my changes to the commit structures.
Simplify the breakit production.  Debug code cleanup.
Another instrumentation step.
Instability is somewhere in the commit merge logic.
Commit entries are being generaated in a consisrent order...

...is something rearranging them?
And there's the bug. Either the cast in compare_names() is wrong...

...or the name fields in the rev_file structures have been trashed.
Verifying that rev_file names are visible.
Remove presorting of rev_file pointers when a directory was packed.

That sort was the order-instability bug.  Rather than try to patch
dodgy code involving casts from (void*) I've just yanked it; the
fileops get sorted in the export phase anyway.

This will degrade space efficiency in the relatively uncommon case
that a CVS commit involves file in multiple directories.  On the other
hand, it will speed up processing slightly.
Order-instability bug fixed - tests work both within Emacs and in shell.
Clean up some ebris from the order instability testing.
Restore the tests to a state consistent with this bersion.

Required a rebuild of basic.chk, because feneraytion of default .gitignores
has been backed out.
Fix the tree comparison machinery in testlifter.py so it ignores .gitignore.

Necessary because we're about to re-merge the patch that generates them.
Re-merge the fix to generarte .gitignore defayults properly...

...now that failures in that aren't confounded with order-instability problems.
Code is finally in the shape it was supposed to be gor release 1.14. :-(

Order-instability is fixed, all tests passing.
Add a fatal error check for when revision numbers iin input get too long.

All regression tests pass.
Turn off rbtree debufgging by default - speeds ot up significantly.
Rationalise debug flags
Add ORDERDEBUG to the commented-out flags in the Makefile.