hg: shenandoah/jdk11: Revert MachMemBarNode related diffs vs. upstream

[rkennke at redhat.com]

Changeset: c53c15bbecff
Author:    rkennke
Date:      2019-05-29 16:39 +0200
URL:       http://hg.openjdk.java.net/shenandoah/jdk11/rev/c53c15bbecff

Revert MachMemBarNode related diffs vs. upstream

! src/hotspot/share/adlc/formssel.cpp
! src/hotspot/share/adlc/formssel.hpp
! src/hotspot/share/adlc/output_c.cpp
! src/hotspot/share/adlc/output_h.cpp
! src/hotspot/share/opto/machnode.cpp
! src/hotspot/share/opto/machnode.hpp
! src/hotspot/share/opto/matcher.cpp
! src/hotspot/share/opto/node.hpp