RFR: Add missing UseTLAB check in allocation path

[Stefan Karlsson]

Hi all,

There's a missing UseTLAB check in the allocation path, causing 
intermittent test failures when running with -XX:-UseTLAB:

http://cr.openjdk.java.net/~stefank/zgc/zCheckUseTLAB/webrev.01/

Thanks,
StefanK