Fatalized non-unicode warnings skip regex optimization

Fatalized non-unicode warnings skip regex optimization

This makes sure that fatalized non-unicode warnings actually get output.
For example \p{Line_Break=CR} would normally get optimized into an EXACT
node.  But if the user has made non-unicode warnings fatal indicating
they want to be sure not to try to even match such code points, the
optimization is skipped so that the checks are made.

Documentation for this change will be in a future commit.