$NetBSD$

Make prefix settable from the environment.

--- Makefile.orig	2013-10-23 17:58:02.000000000 +0000
+++ Makefile
@@ -1,6 +1,6 @@
 version := $(strip $(shell cat VERSION))
 series := $(strip $(shell cat SERIES))
-prefix := /usr
+prefix ?= /usr/pkg
 build_dir := "."
 dist_name = fs-uae-launcher-$(version)
 dist_dir := $(build_dir)/$(dist_name)
