Remove the unaligned load intrinsics in favor of using native unaligned loads.

Remove the unaligned load intrinsics in favor of using native unaligned loads.

Now that we have a first-class way to represent unaligned loads, the unaligned
load intrinsics are superfluous.

First part of <rdar://problem/8460511>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129401 91177308-0d34-0410-b5e6-96231b3b80d8