https://github.com/KhronosGroup/EGL-Registry/pull/43 made eglplatform.h
include X11 headers on Mac OS, which aren't pre-installed and breaks
the Chrome build.

https://github.com/KhronosGroup/EGL-Registry/issues/52

Change-Id: I73e3c11244a07e269684323ce76cc9700fe9c1aa
Reviewed-on: https://swiftshader-review.googlesource.com/19088Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>