False positive when exporting a pointer to a loop variable field.

[joeblubaugh]

Like so:

package main

import "fmt"

func main() {
	type S struct {
		I int
	}

	structs := []S{S{1}, S{2}}

	var myI *int
	for _, s := range structs {
		myI = &s.I
	}

	fmt.Println(*myI)
}

We do this a fair amount in my team's code, and it feels awkward to introduce a second variable like

i := s.I
myI = &i

or to use a //nolint directive.

[kyoh86]

This is a linter to find the matter like such code.
Please read README.md.