explicitly undefine NDEBUG in CFLAGS.

makefile

@@ -24,21 +24,21 @@ ISWIN := $(if $(filter linux darwin freebsd netbsd openbsd,$(KERNEL)),0,1)
 
 # profiles
 ifeq ($(DEBUG),1)         # check whether we're debugging
-CFLAGS  += -Og -g
+CFLAGS  += -UNDEBUG -Og -g
 PROF    := dbg
 ifeq ($(ISWIN),0)
 CFLAGS  += -fsanitize=address,undefined
 LDFLAGS += -fsanitize=address,undefined
 endif
 else ifeq ($(DEBUG),test) # check whether we're perhaps testing
-CFLAGS  += -O2 -g
+CFLAGS  += -UNDEBUG -O2 -g
 PROF    := test
 ifeq ($(ISWIN),0)
 CFLAGS  += -fsanitize=address
 LDFLAGS += -fsanitize=address
 endif
 else                      # otherwise, assume release
-CFLAGS  += -O2 -DNDEBUG
+CFLAGS  += -DNDEBUG -O2
 PROF    := rel
 endif