Get rid of ambiguous overload for xgetbv.

Get rid of ambiguous overload for xgetbv.

The patch that broke this was assuming the signature of xgetbv was
_xgetbv(int). This lead to that there were no exact match for the
function resolver, thus the ambiguity.

Apparently, the signature of _xgetbv is _xgetbv(unsigned int).
Changing the static xgetbv to uint makes the match exact, thus no more
ambiguity.

Change-Id: I8db95e00a9fef264d7a1f84d02bb929db84e6e5a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@digia.com>