Updated make file to use DESTDIR

Makefile

@@ -1,11 +1,14 @@
 CC=gcc
 PROGS=snebu
 SCRIPTS=snebu-client
+PREFIX=/usr/local
+BINDIR=$(PREFIX)/bin
 all: $(PROGS)
 snebu: snebu.c
 	$(CC) $< -o $@ -l sqlite3 -l crypto -l lzo2 -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -O3
-install: $(PROGS)
-	cp -p $(PROGS) $(SCRIPTS) /usr/local/bin/
+install: $(PROGS) $(SCRIPTS)
+	mkdir -p $(DESTDIR)$(BINDIR)
+	cp -f $(PROGS) $(SCRIPTS) $(DESTDIR)$(BINDIR)/
 clean:
 	rm -f $(PROGS)