nrf/Makefile: Remove -fstack-usage.
fstack-usage is not supported by Clang and old GCC versions.
@@ -102,7 +102,6 @@ endif
CFLAGS += $(CFLAGS_MCU_$(MCU_SERIES))
CFLAGS += $(INC) -Wall -Werror -g -ansi -std=gnu99 -nostdlib $(COPT) $(NRF_DEFINES) $(CFLAGS_MOD)
CFLAGS += -fno-strict-aliasing
-CFLAGS += -fstack-usage
CFLAGS += -Iboards/$(BOARD)
CFLAGS += -DNRF5_HAL_H='<$(MCU_VARIANT)_hal.h>'
CFLAGS += $(CFLAGS_LTO)
