Fix asserts appearing in release builds

Also fix warnings generated in release builds when assert code
is absent.

Change-Id: I45b9173d3888f9e93e98eb5b4fdc06727ba5cbf4
diff --git a/Makefile b/Makefile
index 7938318..f64a700 100644
--- a/Makefile
+++ b/Makefile
@@ -154,6 +154,8 @@
 CFLAGS			+= 	-g
 # -save-temps -fverbose-asm
 ASFLAGS			+= 	-g -Wa,--gdwarf-2
+else
+CFLAGS			+=	-DNDEBUG=1
 endif