RFR(xs): 8198269: Allow GCCauseSetter to be used outside of safepoints

[Stefan Johansson]

On 2018-02-16 14:46, Per Liden wrote:
> Patch to remove two overly aggressive asserts, to allow a GC to 
> register the cause outside of a safepoint. Concurrent GC's (like ZGC) 
> typically want to do this.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8198269
> Webrev: http://cr.openjdk.java.net/~pliden/8198269/webrev.0/
>
Looks good,
Stefan
> /Per