build with old GNU Make (3.79.1) causes error

[jg1uaa]

Dropbear is good server software for old Linux distro which cannot talk with modern SSH client.
Recently I found dropbear-2024.84 and 2024.85 could not build on Vine Linux 2.5 (GNU Make 3.79.1) like this.

ranlib libtommath.a
make[1]: Leaving directory `/home/uaa/dropbear-2024.84/libtommath'
make: *** No rule to make target `obj/dbutil.o', needed by `dropbear'.  Stop.
[uaa@localhost dropbear-2024.84]$

libtommath.a has built successfully, but error for obj/dbutil.o prevents building.
I think old GNU Make cannot handle this.

$(OBJ_DIR)/%.o: $(srcdir)/%.c $(HEADERS) | $(OBJ_DIR)
        $(CC) $(CFLAGS) $(CPPFLAGS) $< -o $@ -c

[mkj]

The | "order-only prerequisite" doesn't seem to be a new GNU make addition, so I'm not sure why it would fail.