Remove background checking code

cmd/restic/background.go

@@ -1,9 +0,0 @@
-// +build !linux
-
-package main
-
-// IsProcessBackground should return true if it is running in the background or false if not
-func IsProcessBackground() bool {
-	//TODO: Check if the process are running in the background in other OS than linux
-	return false
-}

cmd/restic/background_linux.go

@@ -1,21 +0,0 @@
-package main
-
-import (
-	"syscall"
-	"unsafe"
-
-	"github.com/restic/restic/internal/debug"
-)
-
-// IsProcessBackground returns true if it is running in the background or false if not
-func IsProcessBackground() bool {
-	var pid int
-	_, _, err := syscall.Syscall(syscall.SYS_IOCTL, uintptr(syscall.Stdin), syscall.TIOCGPGRP, uintptr(unsafe.Pointer(&pid)))
-
-	if err != 0 {
-		debug.Log("Can't check if we are in the background. Using default behaviour. Error: %s\n", err.Error())
-		return false
-	}
-
-	return pid != syscall.Getpgrp()
-}