They are not needed, and due to them there was a call to _xgetbv()
without a declaration of the function.  This used to work because we
implicitly included intrin.h in all translation units with clang-cl, but
we want to stop doing that.

BUG=chromium:592745
R=fbarchard@google.com

Review URL: https://codereview.chromium.org/1780473003 .