examples/javascript: Correctly declare dependency on script files.

Custom targets should be added to BUILDDEPS. Without this patch
`make -j clean all" fails because of weird race condition (trying
to clean while building is kind of contradictory anyways.)

examples/javascript/Makefile

@@ -35,21 +35,21 @@ endif
 # Add the package for Jerryscript
 USEPKG += jerryscript
 
-include $(RIOTBASE)/Makefile.include
+JS_PATH = $(BINDIR)/js/$(MODULE)
 
-JS_PATH := $(BINDIR)/js/$(MODULE)
 # add directory of generated *.js.h files to include path
 CFLAGS += -I$(JS_PATH)
 
 # generate .js.h header files of .js files
 JS = $(wildcard *.js)
-JS_H := $(JS:%.js=$(JS_PATH)/%.js.h)
+JS_H = $(JS:%.js=$(JS_PATH)/%.js.h)
 
-$(JS_PATH)/:
-	@mkdir -p $@
+BUILDDEPS += $(JS_H) $(JS_PATH)/
 
-$(JS_H): | $(JS_PATH)/
-$(JS_H): $(JS_PATH)/%.js.h: %.js
-	xxd -i $< | sed 's/^unsigned/const unsigned/g' > $@
+include $(RIOTBASE)/Makefile.include
+
+$(JS_PATH)/:
+	$(Q)mkdir -p $@
 
-$(RIOTBUILD_CONFIG_HEADER_C): $(JS_H)
+$(JS_H): $(JS_PATH)/%.js.h: %.js | $(JS_PATH)/
+	$(Q)xxd -i $< | sed 's/^unsigned/const unsigned/g' > $@