[16] RFFR(S) 8249165: Remove unneeded nops introduced by 8234160 changes

[Vladimir Kozlov]

https://cr.openjdk.java.net/~kvn/8249165/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8249165

Check for branch instruction at the and of code block when generating NOPs to align it.
I did not see significant difference in performance in our regular benchmarks (jvm2008, JBB) but I think it is still 
good to do.

Thanks,
Vladimir