Add new cmake option to disable the generation of DFU file (which needs adafruit-nrfutil on the build machine) : BUILD_DFU (disabled by default, enabled in docker build).

docker/build.sh

@@ -63,6 +63,7 @@ CmakeGenerate() {
     -DUSE_OPENOCD=1 \
     -DARM_NONE_EABI_TOOLCHAIN_PATH="$TOOLS_DIR/$GCC_ARM_VER" \
     -DNRF5_SDK_PATH="$TOOLS_DIR/$NRF_SDK_VER" \
+    -DBUILD_DFU=1 \
     "$SOURCES_DIR"
   cmake -L -N .
 }