make.deprules

#
# Automatic dependency generation when it can't find
# the .d file.  See Section 4.14 of GNU make.
#
# (The -M to gcc does this.  Also, dump error messages about not being
# able to find a header file to /dev/null.  Let the user figure it out 
# when he tries to compile.)
#
ifneq ($(MAKECMDGOALS),clean)
%.d: %.c
	@set -e; rm -f $@; \
	$(CC) -M $(CPPFLAGS) $(CFLAGS) $< > $@.$$$$ 2>/dev/null; \
	sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
	rm -f $@.$$$$
endif