failpoint in anonymous function can not be enable

[lysu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.

package testpkg

import (
    "fmt"

    "github.com/pingcap/failpoint"
)

func test() {
    func() {
        failpoint.Inject("testPoint", func() {
            fmt.Println()
        })
    }()
}

then failpoint-ctl enable~

2. What did you expect to see?

func test() {
    func() {
        if _, ok := failpoint.Eval(_curpkg_("testPoint")); ok {
            fmt.Println()
        }
    }()
}

3. What did you see instead?

func test() {
    func() {
        failpoint.Inject("testPoint", func() {
            fmt.Println()
        })
    }()
}

4. Versions of the failpoint

failpoint-ctl version (run failpoint-ctl -V):

ReleaseVersion None
BuildTS None
GitHash None
GitBranch None
GoVersion None

newest tidb master