Aleksey reported shenandoah/jdk builds broken on Windows and Linux.

c:\cygwin64\home\windows\worker\shenandoah-jdkX-windows\build\src\hotspot\share\gc/shenandoah/shenandoahLock.hpp(72)
: error C2653: 'SafepointSynchronize' : is not a class or namespace name
c:\cygwin64\home\windows\worker\shenandoah-jdkX-windows\build\src\hotspot\share\gc/shenandoah/shenandoahLock.hpp(72)
: error C3861: 'is_at_safepoint': identifier not found

and

/home/buildbot/worker/shenandoah-jdkX-linux/build/src/hotspot/share/gc/shenandoah/shenandoahLock.cpp:26:
/home/buildbot/worker/shenandoah-jdkX-linux/build/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp: In
member function ‘void ShenandoahLock::assert_owned_by_current_thread_or_safepoint()’:
/home/buildbot/worker/shenandoah-jdkX-linux/build/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp:73:13:
error: ‘SafepointSynchronize’ has not been declared
            (SafepointSynchronize::is_at_safepoint() && thr->is_VM_thread()),
             ^
/home/buildbot/worker/shenandoah-jdkX-linux/build/src/hotspot/share/utilities/debug.hpp:56:9: note:
in definition of macro ‘vmassert’
   if (!(p)) { \
         ^
/home/buildbot/worker/shenandoah-jdkX-linux/build/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp:72:5:
note: in expansion of macro ‘assert’
     assert((_state == locked && _owner == thr) ||
     ^~~~~~