[gentoo-user] How does Gentoo deal with GCC's header fixes?

[Nikos Chantziaras]

When building GCC, it will scan all headers in /usr/include and apply 
fixes to them, and then copy them and use the modified versions.  Now a 
binary distro (AFAIK) will ship the GCC modified headers, so there's no 
problem.

Gentoo on the other hand will work as intended by GCC only if the user 
re-emerges GCC after every time a package is emerged that installs 
headers.  Obviously, no user does that.

So the question is simple; does Gentoo deal with this problem in any way?