sink tuples by values (nim-lang#24731)

A reduced case
```nim
type AnObject = tuple
  a: string
  b: int
  c: int

proc mutate(a: sink AnObject) =
  `=wasMoved`(a)
  echo 1

# echo "Value is: ", obj.value
proc bar =
  mutate(("1.2", 0, 0))

bar()
```

compiler/ccgutils.nim

@@ -101,7 +101,11 @@ proc ccgIntroducedPtr*(conf: ConfigRef; s: PSym, retType: PType): bool =
       result = true           # ordinary objects are always passed by reference,
                               # otherwise casting doesn't work
   of tyTuple:
-    result = (getSize(conf, pt) > conf.target.floatSize*3) or (optByRef in s.options)
+    if s.typ.kind == tySink:
+      # it's a sink, so we pass it by value
+      result = false
+    else:
+      result = (getSize(conf, pt) > conf.target.floatSize*3) or (optByRef in s.options)
   else:
     result = false
   # first parameter and return type is 'lent T'? --> use pass by pointer

tests/arc/tarcmisc.nim

@@ -33,6 +33,7 @@ copying
 123
 42
 @["", "d", ""]
+mutate: 1
 ok
 destroying variable: 20
 destroying variable: 10
@@ -882,3 +883,18 @@ proc test_18070() = # bug #18070
   doAssert msg == "", "expected empty string but got: " & $msg
 
 test_18070()
+
+type AnObject = tuple
+  a: string
+  b: int
+  c: int
+
+proc mutate(a: sink AnObject) =
+  `=wasMoved`(a)
+  echo "mutate: 1"
+
+# echo "Value is: ", obj.value
+proc bar =
+  mutate(("1.2", 0, 0))
+
+bar()