[REVIEW] Hide BIT_* macros from userland code

From: Stefan Esser <se_at_freebsd.org>
Date: Thu, 02 Dec 2021 16:26:55 UTC
I have created

	https://reviews.freebsd.org/D33235

to remove the BIT_* macros used in the kernel from the userland API.

They conflict with differing definitions in some 3rd party code and
lead to compile issues in a number of ports (via CPU_* macros based
on the BIT_* macros).

See PR259787 https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=259787
for an example of such a problem.