fixing EYE JITI loss

For some particular use cases we experience JITI loss and I made
a simplified case at https://github.com/josd/eyejiti for which
the speed drop is a factor 50.

The proposed is actually fixing the issue and at least all our other
test cases run fine.

The best_index->tried_better_better is created in firstClause(...)
and all the bits cleared and the set_bit happens in bestHash(...).
But we don't claim a full understanding :-)