Makefile: enable Cooja to change BUILD_DIR
Allow Cooja to select a different BUILD_DIR
through environment variables.
This is a way to ensure that the CI tests
work without requiring "make clean" in every
csc file.
@@ -69,7 +69,7 @@ COOJA_PATH ?= $(CONTIKI_NG_TOOLS_DIR)/cooja
JAVA = java
GRADLE = $(COOJA_PATH)/gradlew
-BUILD_DIR = build
+BUILD_DIR ?= build
BUILD_DIR_TARGET = $(BUILD_DIR)/$(TARGET)
BUILD_DIR_TARGET_BOARD = $(BUILD_DIR_TARGET)/$(BOARD)
# If BOARD was empty, make sure we don't end up with a sequence of slashes
