More backreference performance improvements [take 2]

[Jack Howarth]

Isamu,
    I am unclear from your last response to Bonzini if you were
concurring with adding the 60% optimization patches for regex into
glibc cvs (since it doesn't rely on cache profiling) or if you
were still wanting that to wait for your rewrite. Could you clarify
that in case you in fact were okay with those changes going into
glibc cvs?
                                    Jack