Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add memmove() to the kernel, making the kernel compile with Clang.

When copying big structures, LLVM generates calls to memmove(), because
it may not be able to figure out whether structures overlap. This caused
linker errors to occur. memmove() is now implemented using bcopy().
Ideally it would be the other way around, but that can be solved in the
future. On ARM we don't do add anything, because it already has
memmove().

Discussed on: arch@
Reviewed by: rdivacky