hg: shenandoah/jdk: Should return zero actual allocated size when allocation failed

[zgu at redhat.com]

Changeset: dd4dd4959007
Author:    zgu
Date:      2018-06-14 16:11 -0400
URL:       http://hg.openjdk.java.net/shenandoah/jdk/rev/dd4dd4959007

Should return zero actual allocated size when allocation failed

! src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp