fix: comma in exclude pattern leads to unexpected results

[ldez]

Fixes #665

to check the PR:

main.go

package main

import (
	"fmt"
)

func main() {
	foo := "get"
	bar := "get"
	more := "get"
	again := "get"

	fmt.Println(foo+bar+more, again)

	goo()
}

func goo() {
	foo := "example"
	bar := "example"
	more := "example"
	again := "example"

	fmt.Println(foo+bar+more, again)
}

.golangci.yml

linters:
  disable-all: true
  enable:
    - goconst

issues:
  exclude:
    - string .get. has \d+ occurrences, make it a constant

before the PR:

$ golangci-lint run

after the PR:

$ ./golangci-lint run
main.go:19:9: string `example` has 4 occurrences, make it a constant (goconst)
        foo := "example"
               ^

[bombsimon]

LGTM!