icedtea 7 backport of 8154537: AArch64: some integer rotate instructions are never emitted

[Roland Westrelin]

I'd like to have 8154537 backported to icedtea 7 (but I don't have
commit rights). I verified the patch:

http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/52cfeb90ea8b

applies cleanly, the build works and the bug is indeed fixed in icedtea
7 once the patch is applied.

Thanks,
Roland.