can-utils: Don't overwrite PREFIX and DESTDIR when provided via the environment

For creating a Debian package providing PREFIX and DESTDIR via the
environment is the easiest option. So use ?= to assign these two
variables to honor the values in the environment.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

diff --git a/Makefile b/Makefile
index c3e6d9c..2f79ee7 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -38,8 +38,8 @@
 #
 #  Send feedback to <linux-can@vger.kernel.org>
 
-DESTDIR =
-PREFIX = /usr/local
+DESTDIR ?=
+PREFIX ?= /usr/local
 
 MAKEFLAGS = -k