Linuxulator depends on a fundamental kernel settings such as SMP. Many
of them listed in opt_global.h which is not generated while building
modules outside of a kernel and such modules never match real cofigured
kernel.

So, we should prevent our users from building obviously defective modules.

Therefore, remove the root cause of the building of modules outside of a
kernel - the possibility of building modules with DEBUG or KTR flags.
And remove all of DEBUG printfs as it is incomplete and in threaded
programms not informative, also a half of system call does not have DEBUG
printf. For debuging Linux programms we have dtrace, ktr and ktrace ability.

PR: 222861
Reviewed by: trasz
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D20178