Enable CI testing on BSD

[ianfixes]

I can only imagine that this will require running a BSD VM inside Travis CI, and that things will get weird. The only alternative is to solicit money from the community to pay for cirrus CI build time.

See discussion at cebix/macemu#176

[FreeBSD-pzn]

FPU issue is:

obj/fpu_ieee.o: In function `fpuop_arithmetic(unsigned int, unsigned int)':
/home/pzn.oleg/prg/macemu/BasiliskII/src/Unix/./../uae_cpu/fpu/fpu_ieee.cpp:1883:
warning: powl has lower than advertised precision
*************

I got a message above at the assembly stage Basilisk II,
as a result program Calculator does not working.