fixes #24760; Noncopyable base type ignored (#24777)

fixes #24760

I tried `incl` `tfHasAsgn` to nontrivial assignment, but that solution
seems to break too many things. Instead, in this PR, `passCopyToSink`
now checks nontrivial assignment

(cherry picked from commit e958f4a3cd)

tests/arc/t24760.nim

@@ -0,0 +1,20 @@
+discard """
+  matrix: "--mm:orc"
+  errormsg: "=dup' is not available for type <B>, which is inferred from unavailable '=copy'; requires a copy because it's not the last read of 'b'; another read is done here: t24760.nim(19, 8); routine: g"
+"""
+
+type
+  A {.inheritable.} = object
+  B = object of A
+
+proc `=copy`(a: var A, x: A) {.error.}
+#proc `=copy`(a: var B, x: B) {.error.}
+
+proc ffff(v: sink B) =
+  echo v
+
+proc g() =
+  var b: B
+  ffff(b)
+  ffff(b)
+g()