RFR 8213711 (XS): Zero build broken after JDK-8213199 (GC abstraction for Assembler::needs_explicit_null_check())

[Aleksey Shipilev]

Bug:
  https://bugs.openjdk.java.net/browse/JDK-8213711

Fix is to add Zero declaration for the method added in JDK-8213199:

8213711: Zero build broken after JDK-8213199 (GC abstraction for Assembler::needs_explicit_null_check())
Reviewed-by: XXX

diff -r 5643a5bff514 -r 919dde170921 src/hotspot/cpu/zero/assembler_zero.hpp
--- a/src/hotspot/cpu/zero/assembler_zero.hpp   Sat Nov 10 09:06:33 2018 -0500
+++ b/src/hotspot/cpu/zero/assembler_zero.hpp   Sat Nov 10 18:15:49 2018 +0100
@@ -47,6 +47,7 @@
   void align(int modulus);
   void bang_stack_with_offset(int offset);
   bool needs_explicit_null_check(intptr_t offset);
+  bool uses_implicit_null_check(void* address);
   RegisterOrConstant delayed_value_impl(intptr_t* delayed_value_addr,
                                         Register tmp, int offset);
  public:


Testing: x86_64 {Zero,Server} builds

Thanks,
-Aleksey