Improve recursive struct detection

[keynmol]

This was surprising:

typedef struct FT_ListNodeRec_ *FT_ListNode;

typedef struct FT_ListNodeRec_ {
  FT_ListNode prev;
  FT_ListNode next;
  void *data;

} FT_ListNodeRec;

Generated code doesn't compile:

r] illegal cyclic type reference: alias scala.scalanative.unsafe.Ptr[ft.structs.FT_ListNodeRec_] of type FT_ListNode refers back to the type itself
[error]
[error]  Run with -explain-cyclic for more details.
[error]   opaque type FT_ListNode = Ptr[FT_ListNodeRec_]
[error]               ^
[error] /var/folders/jr/4vy422xj6zs44hsn5d1_b4g40000gn/T/15695818354923484461/.scala-build/15695818354923484461_12528d1359-a97710677f/src_generated/main/stdin.scala:16:36
[error] Found:    scala.scalanative.unsafe.Tag.Ptr[ft.structs.FT_ListNodeRec_]
[error] Required: scala.scalanative.unsafe.Tag[ft.aliases.FT_ListNode]
[error]     given _tag: Tag[FT_ListNode] = Tag.Ptr[FT_ListNodeRec_](FT_ListNodeRec_._tag)
[error]                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error] /var/folders/jr/4vy422xj6zs44hsn5d1_b4g40000gn/T/15695818354923484461/.scala-build/15695818354923484461_12528d1359-a97710677f/src_generated/main/stdin.scala:19:48
[error] Found:    (v : ft.aliases.FT_ListNode)
[error] Required: scala.scalanative.unsafe.Ptr[ft.structs.FT_ListNodeRec_]
[error]       inline def value: Ptr[FT_ListNodeRec_] = v
[error]                                                ^
[error] /var/folders/jr/4vy422xj6zs44hsn5d1_b4g40000gn/T/15695818354923484461/.scala-build/15695818354923484461_12528d1359-a97710677f/src_generated/main/stdin.scala:72:3
[error] exports are only allowed from objects and classes, they can not belong to local blocks
[error]   export _root_.ft.structs.FT_ListNodeRec
[error]   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[error] /var/folders/jr/4vy422xj6zs44hsn5d1_b4g40000gn/T/15695818354923484461/.scala-build/15695818354923484461_12528d1359-a97710677f/src_generated/main/stdin.scala:73:3
[error] exports are only allowed from objects and classes, they can not belong to local blocks
[error]   export _root_.ft.structs.FT_ListNodeRec_
[error]   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error compiling project (Scala 3.4.1, Scala Native 0.5.1)

Here's the code generated by 0.1.4

package ft

import _root_.scala.scalanative.unsafe.*
import _root_.scala.scalanative.unsigned.*
import _root_.scala.scalanative.libc.*
import _root_.scala.scalanative.*

object aliases:
  import _root_.ft.aliases.*
  import _root_.ft.structs.*
  /**
   * [bindgen] header: repro.h
  */
  opaque type FT_ListNode = Ptr[FT_ListNodeRec_]
  object FT_ListNode: 
    given _tag: Tag[FT_ListNode] = Tag.Ptr[FT_ListNodeRec_](FT_ListNodeRec_._tag)
    inline def apply(inline o: Ptr[FT_ListNodeRec_]): FT_ListNode = o
    extension (v: FT_ListNode)
      inline def value: Ptr[FT_ListNodeRec_] = v

object structs:
  import _root_.ft.aliases.*
  import _root_.ft.structs.*
  /**
   * [bindgen] header: repro.h
  */
  opaque type FT_ListNodeRec = CStruct3[FT_ListNode, FT_ListNode, Ptr[Byte]]
  object FT_ListNodeRec:
    given _tag: Tag[FT_ListNodeRec] = Tag.materializeCStruct3Tag[FT_ListNode, FT_ListNode, Ptr[Byte]]
    def apply()(using Zone): Ptr[FT_ListNodeRec] = scala.scalanative.unsafe.alloc[FT_ListNodeRec](1)
    def apply(prev : FT_ListNode, next : FT_ListNode, data : Ptr[Byte])(using Zone): Ptr[FT_ListNodeRec] = 
      val ____ptr = apply()
      (!____ptr).prev = prev
      (!____ptr).next = next
      (!____ptr).data = data
      ____ptr
    extension (struct: FT_ListNodeRec)
      def prev : FT_ListNode = struct._1
      def prev_=(value: FT_ListNode): Unit = !struct.at1 = value
      def next : FT_ListNode = struct._2
      def next_=(value: FT_ListNode): Unit = !struct.at2 = value
      def data : Ptr[Byte] = struct._3
      def data_=(value: Ptr[Byte]): Unit = !struct.at3 = value

  /**
   * [bindgen] header: repro.h
  */
  opaque type FT_ListNodeRec_ = CStruct3[FT_ListNode, FT_ListNode, Ptr[Byte]]
  object FT_ListNodeRec_ :
    given _tag: Tag[FT_ListNodeRec_] = Tag.materializeCStruct3Tag[FT_ListNode, FT_ListNode, Ptr[Byte]]
    def apply()(using Zone): Ptr[FT_ListNodeRec_] = scala.scalanative.unsafe.alloc[FT_ListNodeRec_](1)
    def apply(prev : FT_ListNode, next : FT_ListNode, data : Ptr[Byte])(using Zone): Ptr[FT_ListNodeRec_] = 
      val ____ptr = apply()
      (!____ptr).prev = prev
      (!____ptr).next = next
      (!____ptr).data = data
      ____ptr
    extension (struct: FT_ListNodeRec_)
      def prev : FT_ListNode = struct._1
      def prev_=(value: FT_ListNode): Unit = !struct.at1 = value
      def next : FT_ListNode = struct._2
      def next_=(value: FT_ListNode): Unit = !struct.at2 = value
      def data : Ptr[Byte] = struct._3
      def data_=(value: Ptr[Byte]): Unit = !struct.at3 = value

object types:
  export _root_.ft.structs.*
  export _root_.ft.aliases.*

object all:
  export _root_.ft.aliases.FT_ListNode
  export _root_.ft.structs.FT_ListNodeRec
  export _root_.ft.structs.FT_ListNodeRec_