RFR: Fix builds on unsupported platforms after C2 changes

[Roman Kennke]

Yes yes. ;-)

Am 5. September 2018 10:46:56 MESZ schrieb Aleksey Shipilev <shade at redhat.com>:
>sh/jdk build is broken on non-Shenandoah platforms because:
>
>/pool/buildbot/slaves/sobornost/shenandoah-jdkX/build/src/hotspot/share/opto/cfgnode.cpp:
>In
>function ‘Node* is_x2logic(PhaseGVN*, PhiNode*, int)’:
>/pool/buildbot/slaves/sobornost/shenandoah-jdkX/build/src/hotspot/share/opto/cfgnode.cpp:1319:11:
>error: invalid use of incomplete type ‘class BarrierSetC2’
>   in1 = bs->peek_thru_gc_barrier(in1);
>           ^~
>/pool/buildbot/slaves/sobornost/shenandoah-jdkX/build/src/hotspot/share/gc/shared/barrierSet.hpp:38:7:
>note: forward declaration of ‘class BarrierSetC2’
> class BarrierSetC2;
>       ^~~~~~~~~~~~
>
>This is due to missing include for barrierSetC2, which is otherwise
>transitively included via
>shenandoahSupport.hpp. Fix:
>
>diff -r b67a4350c0b0 src/hotspot/share/opto/cfgnode.cpp
>--- a/src/hotspot/share/opto/cfgnode.cpp	Tue Sep 04 12:47:36 2018 -0400
>+++ b/src/hotspot/share/opto/cfgnode.cpp	Wed Sep 05 10:44:06 2018 +0200
>@@ -24,6 +24,8 @@
>
> #include "precompiled.hpp"
> #include "classfile/systemDictionary.hpp"
>+#include "gc/shared/barrierSet.hpp"
>+#include "gc/shared/c2/barrierSetC2.hpp"
> #include "memory/allocation.inline.hpp"
> #include "memory/resourceArea.hpp"
> #include "oops/objArrayKlass.hpp"
>
>Testing: Linux arm32 build
>
>Thanks,
>-Aleksey