parameterize ctrl thread registers cache with entity store, rather than relying on implicit demon-api-provided cache

src/regs/regs.mdesk

@@ -421,7 +421,7 @@ regs_g_reg_code_x86_usage_kind_table:
 {
   `internal U64 regs_block_size_from_architecture(Architecture arch)`;
   `{`;
-    `U64 result = 0;`;
+    `U64 result = 8;`;
     `switch(arch)`;
     `{`;
       `default:{}break;`;