[X86] Replace unaligned store builtins in SSE/AVX intrinsic files with code...

[X86] Replace unaligned store builtins in SSE/AVX intrinsic files with code that will compile to a native unaligned store. Remove the builtins since they are no longer used.

Intrinsics will be removed from llvm in a future commit.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@271214 91177308-0d34-0410-b5e6-96231b3b80d8