hg: jdk9/hs/hotspot: 8157560: Reserve space for allocation prefetch only in builds that support allocation prefetching

[zoltan.majo at oracle.com]

Changeset: 18194796107b
Author:    zmajo
Date:      2016-05-24 09:07 +0200
URL:       http://hg.openjdk.java.net/jdk9/hs/hotspot/rev/18194796107b

8157560: Reserve space for allocation prefetch only in builds that support allocation prefetching
Summary: Create the reserved area only in C2-enabled builds.
Reviewed-by: kvn, thartmann

! src/share/vm/gc/shared/threadLocalAllocBuffer.cpp
! test/runtime/CommandLine/OptionsValidation/TestOptionsWithRanges.java