Search:

Obviously this is not a good way because I'm building a program like gcc for another target.

However I found the solution and so, also, my error: I didn't set up properly sysroot.

I had to...

Yes, I know, and I found _types.h in /usr/include/freebsd/sys.
Now?

I was trying to compile a gcc cross compiler for linux x86_64 (build and host) to freebsd x86_64.
I tried to follow this http://marcelog.github.io/articles/articles.html and then some other guides...