un-xfail test for #8498 and replace prints w/ asserts
auto merge of #11975 : jfager/rust/r8498, r=alexcrichton

Closes #8498
std: Move kinds to libprim
std: Move intrinsics to libprim
std: Move mem to libprim
std: Stop (incorrectly) parameterizing some memcpy functions over RawPtr

This couples ptr and cast in a way that makes it harder to extract these modules.
It also is arguably incorrect since it makes unsafe assumptions that any impl
of RawPtr is for actual pointers.
std: Remove unused bump_box_refcount function
std: Stop using @ in cast module
std: Move cast to libprim
std: Move array_each out of ptr
std: Remove to_option method from RawPtr
std: Move ptr to prim
std: Move swap and replace to prim
std: Move tuple extension methods to prim
std: Move raw to libprim