[aarch64-port-dev ] RFR(xs): UB in os_linux_aarch64.cpp SpinPause

[Severin Gehwolf]

Hi,

This is a follow-up for a fix which went in a while ago:
http://hg.openjdk.java.net/aarch64-port/jdk8u/hotspot/rev/e47e8eaec0b4

The above changeset fixed almost all functions with missing return
values. It did miss SpinPause in os_linux_aarch64.cpp, though.

Here is a webrev which fixes this:
http://cr.openjdk.java.net/~sgehwolf/webrevs/aarch64-port/ub_spinpause/webrev.01/

Without this fix, the current JDK 8 port does not bootcycle-images
build on an OS with GCC 8.

Note: A similar fix got pushed to upstream jdk8u for Zero:
http://hg.openjdk.java.net/jdk8u/jdk8u-dev/hotspot/rev/ca4663e58916

Once reviewed, I'd appreciate if somebody could sponsor this changeset
and get it pushed.

Thanks,
Severin