lib/defines.mk: Don't always set -DDEBUG

The defines.mk file always set -DDEBUG, inherited from the xdp-tools build
system. However, the configure script in this repository doesn't actually
support the PRODUCTION variable, so change the define to only set -DDEBUG
if a DEBUG variable is supplied to 'make'. This way DEBUG can be turned on
with a command-line DEBUG=1 parameter to 'make', but will be unset
otherwise.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Author: tohojo

lib/defines.mk

@@ -22,7 +22,7 @@ LIBBPF_DIR := $(LIB_DIR)/libbpf
 
 DEFINES := -DBPF_DIR_MNT=\"$(BPF_DIR_MNT)\" -DBPF_OBJECT_PATH=\"$(BPF_OBJECT_DIR)\"
 
-ifneq ($(PRODUCTION),1)
+ifeq ($(DEBUG),1)
 DEFINES += -DDEBUG
 endif