The fix for #4914 was wrong and broke other things (see #5149). We

The fix for #4914 was wrong and broke other things (see #5149).  We
can't emit the ffrees before a conditional jump, because we don't want
to ffree the stack registers if the jump isn't taken (d'oh).

This commit fixes it properly, by moving the pass that inserts the
ffrees to *before* we do the jump-shortcutting which introduces the
conditional non-local jumps.