fix: re-import of identical package with sym.typ.cat == binPkgT

[he11olx]

test case:

func main() {
	script1 := `package script
import "encoding/json"
var _ = json.Marshal
`
	script2 := `package script
import "encoding/json"
var _ = json.Marshal
`
	inter := interp.New(interp.Options{GoPath: build.Default.GOPATH})
	_ = inter.Use(stdlib.Symbols)

	inter.Eval(script1)
	_, err := inter.Eval(script2)
	fmt.Println(err)
	// 2:8: json/_.go redeclared in this block
}

Related to: https://github.com/traefik/yaegi/pull/1066/files

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[he11olx]

Looks like not a bug but a feature. But In REPL, executing two import "fmt" will also report errors.

➜  yaegi
> import "fmt"
: 0x14000030120
> import "fmt"
1:21: fmt/_.go redeclared in this block