build: W600-SDK importiert, Firmware-Build und Hello am EVK

Docker-Build mit gcc-arm-none-eabi 4.9-2014q4 (statt Homebrew-Cask) verwendet,
Dockerfile/tools/docker.sh dafür aus Task 13 vorgezogen. cmake/sdk.cmake schont
gcc 4.9 (kennt -fcommon/-Wno-error=... nicht). Zwei zusätzliche SDK-Stubs
(EarlyInit, pre_gpio_config) in src/sys/sdk_stubs.c ergänzt, siehe sdk/PATCHES.md.

tools/flash.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+# Flashes build/<device>/ninlight_<device>.fls over the serial port (runs natively on the Mac).
+# Usage: tools/flash.sh <device> <port-name as listed by `build/host-tools/wm_tool -l`>
+set -euo pipefail
+DEV=${1:?usage: tools/flash.sh <device> <port>}
+PORT=${2:?usage: tools/flash.sh <device> <port>}
+ROOT=$(cd "$(dirname "$0")/.." && pwd)
+TOOL="$ROOT/build/host-tools/wm_tool"
+if [ ! -x "$TOOL" ] || [ "$ROOT/sdk/tools/wm_tool.c" -nt "$TOOL" ]; then
+  mkdir -p "$(dirname "$TOOL")"
+  cc -O2 -w -o "$TOOL" "$ROOT/sdk/tools/wm_tool.c" -lpthread
+fi
+"$TOOL" -c "$PORT" -ds 921600 -rs rts -dl "$ROOT/build/$DEV/ninlight_$DEV.fls"