FreeBSD raspberry pi C compiler strangeness

[Wojciech Puchar]

i wrote my program and tested completely my program on x64 laptop under 
FreeBSD 11

then i compiled this program under FreeBSD on raspberry pi (quite latest 
version downloaded less than 2 months ago).

And program didn't work properly.

Finally i found a problem.

char is signed by default on x64.

On raspberry pi char is unsigned by default.
replacing "char" with "signed char" fixed problem completely.

Why char is unsigned on FreeBSD/raspberry pi?