Fix the error of missing libtuv header file

Initialize and update the git submodule before compiling the dcurl source code
rather than using the libtuv library file.

Makefile

@@ -118,11 +118,11 @@ endif
 
 OBJS := $(addprefix $(OUT)/, $(OBJS))
 
-$(OUT)/test-%.o: tests/test-%.c
+$(OUT)/test-%.o: tests/test-%.c $(LIBTUV_PATH)/include
 	$(VECHO) "  CC\t$@\n"
 	$(Q)$(CC) -o $@ $(CFLAGS) -I $(SRC) $(LIBTUV_INCLUDE) -c -MMD -MF $@.d $<
 
-$(OUT)/%.o: $(SRC)/%.c
+$(OUT)/%.o: $(SRC)/%.c $(LIBTUV_PATH)/include
 	$(VECHO) "  CC\t$@\n"
 	$(Q)$(CC) -o $@ $(CFLAGS) $(LIBTUV_INCLUDE) -c -MMD -MF $@.d $<
 

mk/submodule.mk

@@ -16,6 +16,8 @@ LIBTUV_PLATFORM := $(UNAME_M)-$(UNAME_S)
 # PIC (Position-Independent-Code) library
 LIBTUV_LIBRARY := $(LIBTUV_PATH)/build/$(LIBTUV_PLATFORM)/release/lib/libtuv.o
 
-$(LIBTUV_LIBRARY):
+$(LIBTUV_PATH)/include:
 	git submodule update --init $(LIBTUV_PATH)
+
+$(LIBTUV_LIBRARY):
 	$(MAKE) -C $(LIBTUV_PATH) TUV_BUILD_TYPE=release TUV_CREATE_PIC_LIB=yes