fixes #23524; global variables cannot be analysed when injecting move (#23529)

fixes #23524

```nim
proc isAnalysableFieldAccess*(orig: PNode; owner: PSym): bool =
  ...
  result = n.kind == nkSym and n.sym.owner == owner and
    {sfGlobal, sfThread, sfCursor} * n.sym.flags == {} and
    (n.sym.kind != skParam or isSinkParam(n.sym))
```
In `isAnalysableFieldAccess`, globals, cursors are already rejected

tests/arc/tarcmisc.nim

@@ -727,3 +727,18 @@ block: # bug #23505
 
   discard init(C)
 
+block: # bug #23524
+  type MyType = object
+    a: int
+
+  proc `=destroy`(typ: MyType) = discard
+
+  var t1 = MyType(a: 100)
+  var t2 = t1 # Should be a copy?
+
+  proc main() =
+    t2 = t1
+    doAssert t1.a == 100
+    doAssert t2.a == 100
+
+  main()