xenopsd: change type of reported CPU feature-sets to an abstract type

Internally, feature sets are still strings of hex digits. However. the
goal is for this to become opaque data for xapi.

Signed-off-by: Rob Hoes <[email protected]>

(cherry picked from commit
xapi-project/xen-api@6491e05)

Author: robhoes

xen/xenops_interface.ml

@@ -508,11 +508,11 @@ module Host = struct
     ; model: string
     ; stepping: string
     ; flags: string
-    ; features: int64 array
-    ; features_pv: int64 array
-    ; features_hvm: int64 array
-    ; features_pv_host: int64 array
-    ; features_hvm_host: int64 array
+    ; features: host_cpu_policy
+    ; features_pv: host_cpu_policy
+    ; features_hvm: host_cpu_policy
+    ; features_pv_host: host_cpu_policy
+    ; features_hvm_host: host_cpu_policy
   }
   [@@deriving rpcty]