Ensure our CFLAGS are being used

--- lilo-24.2/src/Makefile	2015-11-21 17:50:25.000000000 -0600
+++ lilo-24.2/src/Makefile	2020-03-19 04:48:25.069499686 -0500
@@ -22,7 +22,7 @@ LD86=ld86 -0
 NASM=nasm
 G=`cat foo1 foo2 | grep version | cut -d " " -f 3`
 
-CFLAGS=$(OPT) -Wall $(PCONFIG)
+CFLAGS+=-Wall $(PCONFIG)
 LIBS=$(DEVMAPPER)
 
 OBJS=lilo.o raid.o map.o geometry.o boot.o device.o common.o bsect.o cfg.o \