[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.

llvm-svn: 271214