EGLAttrib can be a 64-bit type on some configurations, in which case
it needs an explicit cast to be converted to EGLint.

TEST=standalone MSVS 2015 x64 debug build

Change-Id: I6b3e0ae705e8862e079e81e516d6bf99409732e7
Reviewed-on: https://chromium-review.googlesource.com/350411Reviewed-by: Olli Etuaho <oetuaho@nvidia.com>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>