[X86] Use the new unaligned vector typedefs for the loadu/storeu intrinsics pointer arguments.

This matches what gcc does and what was suggested by rnk in PR20670.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@353802 91177308-0d34-0410-b5e6-96231b3b80d8