Merge llvm commits for kernel address and memory sanitizer support

Merge llvm commits for kernel address and memory sanitizer support

Merge commit 99eca1bd9c7a from llvm git (by Mark Johnston):

  [Driver] Enable kernel address and memory sanitizers on FreeBSD

  Test Plan: using kernel ASAN and MSAN implementations in FreeBSD

  Reviewed By: emaste, dim, arichardson

  Differential Revision: https://reviews.llvm.org/D98286

Merge commit f511dc75e4c1 from llvm git (by Mark Johnston):

  [asan] Add an offset for the kernel address sanitizer on FreeBSD

  This is based on a port of the sanitizer runtime to the FreeBSD kernel
  that has been commited as https://cgit.freebsd.org/src/commit/?id=38da497a4dfcf1979c8c2b0e9f3fa0564035c147
  and the following commits.

  Reviewed By: emaste, dim
  Differential Revision: https://reviews.llvm.org/D98285

Requested by:	markj
MFC after:	3 days