RFR: 8234379: ZGC: Do not resize TALBs unless -XX:ResizeTLAB is enabled

[Per Liden]

ZGC currently calls ThreadLocalAllocBuffer::resize() regardless of if 
-XX:ResizeTLAB is enabled or not. This causes the following assert to fail:

#  Internal Error 
(open/src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp:130), 
pid=22060, tid=22069
#  assert(ResizeTLAB) failed: Should not call this otherwise

Bug: https://bugs.openjdk.java.net/browse/JDK-8234379
Webrev: http://cr.openjdk.java.net/~pliden/8234379/webrev.0

/Per