boards/arduino-due: fixed broken flash target

boards/arduino-due/Makefile.include

@@ -11,20 +11,18 @@ export LINK = $(PREFIX)gcc
 export SIZE = $(PREFIX)size
 export OBJCOPY = $(PREFIX)objcopy
 export TERMPROG = $(RIOTBASE)/dist/tools/pyterm/pyterm
+export FLASHER = $(RIOTBOARD)/$(BOARD)/dist/flash.sh
 
 #define the flash-tool and default port depending on the host operating system
 OS := $(shell uname)
 ifeq ($(OS),Linux)
   PORT ?= /dev/ttyACM0
-  FLASHER = stty -F $(PORT) raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255; $(RIOTBOARD)/$(BOARD)/dist/bossac
 else ifeq ($(OS),Darwin)
   PORT ?= $(shell ls -1 /dev/tty.usbmodem* | head -n 1)
-  FLASHER = stty -f $(PORT) raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255; $(RIOTBOARD)/$(BOARD)/dist/bossac_osx
 else
   $(info CAUTION: No flash tool for your host system found!)
   # TODO: add support for windows as host platform
 endif
-export FLASHER
 export PORT
 
 # define build specific options
@@ -36,7 +34,6 @@ export LINKFLAGS += -g3 -ggdb -std=gnu99 $(CPU_USAGE) $(FPU_USAGE) -mlittle-endi
 # linkerscript specified in cpu/Makefile.include
 export LINKFLAGS += -T$(LINKERSCRIPT)
 export OFLAGS += -O binary
-export FFLAGS += -R -e -w -v -b bin/$(BOARD)/$(APPLICATION).hex
 export TERMFLAGS += -p "$(PORT)"
 
 # use the nano-specs of the NewLib when available

boards/arduino-due/dist/flash.sh

+#!/bin/sh
+
+if [ `uname` = "Linux" ]; then
+    stty -F "${PORT}" raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255
+    "${RIOTBOARD}"/"${BOARD}"/dist/bossac  -R -e -w -v -b "${HEXFILE}"
+elif [ `uname` = "Darwin" ]; then
+    stty -f $(PORT) raw ispeed 1200 ospeed 1200 cs8 -cstopb ignpar eol 255 eof 255
+    "${RIOTBOARD}"/"${BOARD}"/dist/bossac_osx -R -e -w -v -b "${HEXFILE}"
+else
+    echo "CAUTION: No flash tool for your host system found!"
+fi