JDK-8293007 breaks the zero VM build, the root cause is that macro AARCH64 and AARCH64_PORT_ONLY are not equivalent in BarrierNSetNMethod::arm_all_nmethods.

Error log:
=== Output from failing command(s) repeated here ===
* For target hotspot_variant-zero_libjvm_objs_barrierSetNMethod.o:
/home/jiangfeilong/workspace/jdk/src/hotspot/share/gc/shared/barrierSetNMethod.cpp: In member function 'void BarrierSetNMethod::arm_all_nmethods()':
/home/jiangfeilong/workspace/jdk/src/hotspot/share/gc/shared/barrierSetNMethod.cpp:136:24: error: incomplete type 'BarrierSetAssembler' used in nested name specifier
   BarrierSetAssembler::clear_patching_epoch();
                        ^~~~~~~~~~~~~~~~~~~~