This pull request is a starting point for discussion on how to integrate
Squint most effectively with amacc.  It may best be done with separate
repos that are tied through modules, but I don't know.

I added a -p option to amacc.c that must currently be used with the
amacc -o option to produce an ELF file that can be optimized with
scripts/peep.  In order for peep to work, a version of squint must
be compiled, e.g. gcc -o squint squint.c .

Example:

% gcc -o amacc-gcc amacc.c -ldl
% ./amacc-gcc -p -o amacc amacc.c
% scripts/disasm amacc > amacc.s
% gcc -o squint squint.c
% scripts/peep amacc
executable file amacc was optimized.
% scripts/disasm amacc > amacc.s.opt
% sdiff -W -d -w 180 amacc.s amacc.s.opt

I have more advanced versions of this that has even beat gcc -O1 for fib.c
and possibly other things, but I suspect you will not like my coding style,
so we will have to discuss.

Add sieve.c to benchmark peephole optimization
Try to clean up some spacing issues

The peephole optimization is 150 lines, but results
in code slightly faster than gcc -O0.  By adding
just a few hundred more lines to the peephole
optimizer, performance can be.  The current
code strikes a balance between being small,
educational, and performant.

I traced back a problem to a use-def analysis across a basic block boundary.
This is not a problem in my private version of Squint which is more complete.
I "dubded down" the algorithm, so it is no longer faster than gcc -O0, but
on the other hand, it is not much slower considering how much dumber the
algorithm is.

Also, so a little more syntax cleanup of squint.c

I'll be honest.  I am flying blind here.  My environment does not
support any of the features required for the AMaCC test environemtn.
I just took a wild guess at what was needed, and will likely have
trouble correcting any errors in what I've done.

My editor automatically expands tabs to spaces.  WHoops!

Again, just duessing since I can't run any of the test scripts, not even make.

Also, fix a use-def overstep dealing with AMaCC comparison construct.

There is a lot here to keep track of.  It would be nice
to address any further issues in a subsequent pull request.
A very small Squint follow-up pull requests is planned to
improve/finalize squint testing and to add an option to
configure squint as a shared library in addition to current
standalone mode.