This allows libANGLE to only be included in libGLESv2 and moves all TLS
data to libGLESv2.dll.

BUG=angle:733

Change-Id: I34f0b47987a5efbe906c290d3ca656142e69ea9a
Reviewed-on: https://chromium-review.googlesource.com/232962Reviewed-by: Jamie Madill <jmadill@chromium.org>
Tested-by: Geoff Lang <geofflang@chromium.org>