rust/vmstate: Fix "cannot infer type" error in vmstate_struct

Rust cannot infer the type (it should be VMStateField) after
Zeroable::ZERO, which cause the compiling error.

To fix this error, call with_varray_flag() after VMStateField's
initialization.

Signed-off-by: Zhao Liu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Paolo Bonzini <[email protected]>

Author: trueptolemy

rust/qemu-api/src/vmstate.rs

@@ -453,13 +453,15 @@ macro_rules! vmstate_struct {
             size: ::core::mem::size_of::<$type>(),
             flags: $crate::bindings::VMStateFlags::VMS_STRUCT,
             vmsd: $vmsd,
-            ..$crate::zeroable::Zeroable::ZERO $(
-                .with_varray_flag($crate::call_func_with_field!(
-                    $crate::vmstate::vmstate_varray_flag,
-                    $struct_name,
-                    $num))
-               $(.with_varray_multiply($factor))?)?
-        }
+            ..$crate::zeroable::Zeroable::ZERO
+         } $(.with_varray_flag(
+                  $crate::call_func_with_field!(
+                      $crate::vmstate::vmstate_varray_flag,
+                      $struct_name,
+                      $num
+                  )
+              )
+           $(.with_varray_multiply($factor))?)?
     };
 }