Use SYS_freebsd6_lseek only if COMPAT_FREEBSD6 is enabled.
Tinderbox had failed with
/scratch/tmp/emaste/freebsd/sys/powerpc/powerpc/exec_machdep.c: In function 'cpu_set_syscall_retval': /scratch/tmp/emaste/freebsd/sys/powerpc/powerpc/exec_machdep.c:882: error: 'SYS_freebsd6_lseek' undeclared (first use in this function) /scratch/tmp/emaste/freebsd/sys/powerpc/powerpc/exec_machdep.c:882: error: (Each undeclared identifier is reported only once /scratch/tmp/emaste/freebsd/sys/powerpc/powerpc/exec_machdep.c:882: error: for each function it appears in.) *** [exec_machdep.o] Error code 1