[aarch64-port-dev ] RFR(XS): 8181906: aarch64: port bugfix for 7009641 to aarch64

[Felix Yang]

Hi,

    Please review webrev: http://cr.openjdk.java.net/~fyang/8181906/webrev/
    We witnessed the same issue on aarch64 jdk8u branch and have fixed the
issue for this branch.
    Like the other ports, the JDK10 & JDK9 aarch64 port should also have
this patch.
    The fix is simple and is only defensive, tested with JTreg hotspot.
    OK to push to this repo: http://hg.openjdk.java.net/jdk10/hs?

Thanks,
Felix