arduino-due: Add -mno-thumb-interwork.

Cortex-M processors only support Thumb instructions (no ARM mode code).

Signed-off-by: Joakim Gebart <joakim.gebart@eistec.se>

boards/arduino-due/Makefile.include

@@ -29,10 +29,10 @@ export PORT
 
 # define build specific options
 export CPU_USAGE = -mcpu=cortex-m3
-export CFLAGS += -ggdb -g3 -std=gnu99 -Os -Wall -Wstrict-prototypes $(CPU_USAGE) $(FPU_USAGE) -mlittle-endian -mthumb -mthumb-interwork -nostartfiles
+export CFLAGS += -ggdb -g3 -std=gnu99 -Os -Wall -Wstrict-prototypes $(CPU_USAGE) $(FPU_USAGE) -mlittle-endian -mthumb -mno-thumb-interwork -nostartfiles
 export CFLAGS += -ffunction-sections -fdata-sections -fno-builtin
 export ASFLAGS += -ggdb -g3 $(CPU_USAGE) $(FPU_USAGE) -mlittle-endian
-export LINKFLAGS += -g3 -ggdb -std=gnu99 $(CPU_USAGE) $(FPU_USAGE) -mlittle-endian -static -lgcc -mthumb -mthumb-interwork -nostartfiles
+export LINKFLAGS += -g3 -ggdb -std=gnu99 $(CPU_USAGE) $(FPU_USAGE) -mlittle-endian -static -lgcc -mthumb -mno-thumb-interwork -nostartfiles
 # linkerscript specified in cpu/Makefile.include
 export LINKFLAGS += -T$(LINKERSCRIPT)
 export OFLAGS += -O binary