firmware: qmod-dfu: disable stack protector

Prevent build failure on debian 9, ubuntu 20.04, 20.10, where
bin/qmod-dfu-flash.elf does not fit the ROM.

Fixes: OS#5081
Change-Id: I9fffe4c323094679062428f41a4246b1c1b30ca2
diff --git a/firmware/Makefile b/firmware/Makefile
index 2d0f62c..b147b0d 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -59,6 +59,11 @@
 BIN = bin
 OBJ = obj/$(BOARD)
 
+# Disable stack protector for code in small ROM regions (OS#5081)
+ifeq ($(BOARD)-$(APP), qmod-dfu)
+CFLAGS_EXTRA ?= -fno-stack-protector
+endif
+
 #-------------------------------------------------------------------------------
 #		Tools
 #-------------------------------------------------------------------------------
@@ -178,6 +183,7 @@
 CFLAGS += -DGIT_VERSION=\"$(GIT_VERSION)\"
 CFLAGS += -DBOARD=\"$(BOARD)\" -DBOARD_$(BOARD)
 CFLAGS += -DAPPLICATION=\"$(APP)\" -DAPPLICATION_$(APP)
+CFLAGS += $(CFLAGS_EXTRA)
 ASFLAGS = -mcpu=cortex-m3 -mthumb -Wall -g $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -D__ASSEMBLY__
 LDFLAGS = -mcpu=cortex-m3 -mthumb -Wl,--cref -Wl,--check-sections -Wl,--gc-sections -Wl,--entry=ResetException -Wl,--unresolved-symbols=report-all -Wl,--warn-common -Wl,--warn-section-align -Wl,--print-memory-usage -Wl,--no-undefined $(LIB)
 #LD_OPTIONAL=-Wl,--print-gc-sections -Wl,--stats