we should avoid code insertion during file dependencies,
such as #include "xxx.h" which has implementations.
This could increase binary size, we can avoid it as possible.
Current patch improves binary size like this:
From: file(2059008) = text(120360) data(8096) bss(80) dec(128536)
To : file(1921832) = text(118429) data(7872) bss(56) dec(126357)
More additional patches will come in to optmize binary size.
