hg: shenandoah/jdk10/hotspot: Add comments in aarch64 matrix barrier, fix comment in x86 matrix barrier.

[roman at kennke.org]

Changeset: 6ba7bc11052b
Author:    rkennke
Date:      2017-09-11 07:41 -0400
URL:       http://hg.openjdk.java.net/shenandoah/jdk10/hotspot/rev/6ba7bc11052b

Add comments in aarch64 matrix barrier, fix comment in x86 matrix barrier.

! src/cpu/aarch64/vm/macroAssembler_aarch64.cpp
! src/cpu/x86/vm/macroAssembler_x86.cpp