build: disable implicit rules

Use ".SUFFIXES:" to disable implicit rules, to control the
build better and to aid debugging.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Makefile

diff --git a/Makefile b/Makefile
index 2652fac..b844dc1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,8 @@
 MAKEFLAGS += --no-print-directory
 
+# disable implicit rules
+.SUFFIXES:
+
 PREFIX ?= /usr
 SBINDIR ?= $(PREFIX)/sbin
 MANDIR ?= $(PREFIX)/share/man