internal/typesinternal: remove NewObjectpathFunc

Updates golang/go#58668
Fixes golang/go#60330

Change-Id: I06bf739e9278028cbafb174b93699fbdfe98882f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/496875
Run-TryBot: Alan Donovan <adonovan@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
Auto-Submit: Alan Donovan <adonovan@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

internal/typesinternal/types.go

@@ -11,8 +11,6 @@ import (
 	"go/types"
 	"reflect"
 	"unsafe"
-
-	"golang.org/x/tools/go/types/objectpath"
 )
 
 func SetUsesCgo(conf *types.Config) bool {
@@ -52,10 +50,3 @@ func ReadGo116ErrorData(err types.Error) (code ErrorCode, start, end token.Pos,
 }
 
 var SetGoVersion = func(conf *types.Config, version string) bool { return false }
-
-// NewObjectpathEncoder returns a function closure equivalent to
-// objectpath.For but amortized for multiple (sequential) calls.
-// It is a temporary workaround, pending the approval of proposal 58668.
-//
-//go:linkname NewObjectpathFunc golang.org/x/tools/go/types/objectpath.newEncoderFor
-func NewObjectpathFunc() func(types.Object) (objectpath.Path, error)