tools/bootconfig: allow overriding CFLAGS assignment

Allow overriding the CFLAGS assignment so that the user can pass in
an outside value.

Link: https://lore.kernel.org/all/20250328183858.1417835-2-bmasney@redhat.com/

Signed-off-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Author: masneyb

tools/bootconfig/Makefile

@@ -10,7 +10,7 @@ srctree := $(patsubst %/,%,$(dir $(srctree)))
 endif
 
 LIBSRC = $(srctree)/lib/bootconfig.c $(srctree)/include/linux/bootconfig.h
-CFLAGS = -Wall -g -I$(CURDIR)/include
+override CFLAGS += -Wall -g -I$(CURDIR)/include
 
 ALL_TARGETS := bootconfig
 ALL_PROGRAMS := $(patsubst %,$(OUTPUT)%,$(ALL_TARGETS))