RFR(S): 8182161: aarch64: combine andr+cbnz into tbnz when possible

[Felix Yang]

Hi,

    Please review: http://cr.openjdk.java.net/~fyang/8182161/webrev/
    Bug: https://bugs.openjdk.java.net/browse/JDK-8182161

    Still exists some instruction combine opportunities in aarch64 hotspot
runtime.
    Tested with JTreg hotspot.
    OK to push to this repo: http://hg.openjdk.java.net/jdk10/hs?

Thanks,
Felix