gcc可以通过-MD命令获取编译的头文件依赖关系。例如gcc -MD demo.c可以得到类似如下：
demo.o: demo.c /usr/include/stdc-predef.h /usr/include/stdio.h \
/usr/include/x86_64-linux-gnu/bits/libc-header-start.h \
/usr/include/features.h /usr/include/features-time64.h \
/usr/include/x86_64-linux-gnu/bits/wordsize.h \
/usr/include/x86_64-linux-gnu/bits/timesize.h \
......
