$NetBSD$

Add NetBSD support. Don't hardcode ${PREFIX}.

--- Makefile.orig	2013-04-14 17:19:41.000000000 +0000
+++ Makefile
@@ -1,5 +1,5 @@
-PREFIX=/usr/local
-BINDIR=$(PREFIX)/bin
+#PREFIX=/usr/local
+BINDIR=${DESTDIR}${PREFIX}/bin
 CFLAGS=-Wall -Werror\
 	-Wformat=2\
 	-g\
@@ -91,3 +91,5 @@ doc/beanstalkd.1 doc/beanstalkd.1.html: 
 	ronn $<
 
 freebsd.o: darwin.c
+
+netbsd.o: darwin.c
