JIT: Correct conversion of cb[n]z to cmp/cond_br pair

This fixes the regression introduced in the fast assembly retry
that was causing excessive bailouts.  The good news is that with
this fix, we're seeing a ~5% boost in Linpack because of the
cb[n]z usage.

Change-Id: Ib4a48dcba809af4343456eae49a90b4a1e3aee9d
1 file changed