kern: Implement most of memory init (all cores hit main, but still more to do)

libraries/libmesosphere/include/mesosphere/arch/arm64/kern_cpu.hpp

@@ -59,6 +59,9 @@ namespace ams::kern::arm64::cpu {
         EnsureInstructionConsistency();
     }
 
+    /* Synchronization helpers. */
+    NOINLINE void SynchronizeAllCores();
+
     /* Cache management helpers. */
     void FlushEntireDataCacheShared();
     void FlushEntireDataCacheLocal();