sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

ubsan: Fix a typo in an error message

- s/asumption/assumption/

Obtained from: NetBSD
MFC after: 1 week

Remove duplicated empty lines from kern/*.c

No functional changes.

Teach the kernel KUBSAN runtime about alignment_assumption

This checks the alignment of a given pointer is sufficient for the
requested alignment asked for. This fixes the build with a recent
llvm/clang.

Sponsored by: DARPA, AFRL

Port the NetBSD ubsan runtime to the FreeBSD kernel.

This allows us to build the ubsan code added in r340189 into the kernel
with the KUBSAN option. This will report when undefined behaviour is
detected in the currently running kernel.

As it can be large, the kernel is 65MB on arm64, loader may not be able to
load the kernel on all architectures so is disabled by default for now.

Sponsored by: DARPA, AFRL

Import the NetBSD micro ubsan code for the kernel.

This imports revision 1.3 of common/lib/libc/misc/ubsan.c from NetBSD, the
micro-ubsan code. It is an implementation of the Undefined Behavior
Sanitizer runtime for use with recent clang and gcc.

The uubsan code will be used in a later commit to implement kubsan to help
find undefined behavior in the kernel.

Sponsored by: DARPA, AFRL