RFR: Fix Minimal build

[Aleksey Shipilev]

Minimal VM fails to build due to our pinning changes:

/pool/buildbot/slaves/sobornost/shenandoah-jdkX/build/src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp:2226:46:
error: invalid use of incomplete type ‘class CollectedHeap’
   if (is_critical_native && !Universe::heap()->supports_object_pinning()) {
                                              ^~
Fix:

diff -r 9003717c5680 src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp
--- a/src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp	Tue Jun 12 18:17:38 2018 +0200
+++ b/src/hotspot/cpu/x86/sharedRuntime_x86_64.cpp	Tue Jun 12 18:39:06 2018 +0200
@@ -33,6 +33,7 @@
 #include "code/nativeInst.hpp"
 #include "code/vtableStubs.hpp"
 #include "gc/shared/gcLocker.hpp"
+#include "gc/shared/collectedHeap.hpp"
 #include "interpreter/interpreter.hpp"
 #include "logging/log.hpp"
 #include "memory/resourceArea.hpp"

Testing: x86_64 minimal VM build

Thanks,
-Aleksey