After all, I studied my mk.conf and I discovered an error. I read that 
you must use
'COPTS +=' instead of just 'COPTS =', so now libgroff builds with no 
problem.

But now there is another problem, related with SSE instruction set 
(-mfpmath=sse). It says this:

*** Failed target:  
/usr/src/sys/arch/i386/stand/bootxx/bootxx_ffsv1/obj/lib/i386/libi386.a
cc1: warnings being treated as errors
/usr/src/sys/arch/i386/stand/lib/pcio.c:1: warning: SSE instruction set 
disabled, using 387 arithmetics
*** Failed target:  pcio.o

This are my COPTS:
COPTS += -O2 -pipe -march=pentium-m -mtune=pentium-m 
-fomit-frame-pointer -mfpmath=sse

I can attach my build.log if you want to, but it is 592K. Any help about 
this matter with SSE?


-- 
Claudio M. Camacho
http://www.claudiocamacho.org