Add a profile mask member to the FunctionsGL structure. BUG=angleproject:883 Change-Id: I3cdf88391e77a26a77e120de0fd32296a2b079d1 Reviewed-on: https://chromium-review.googlesource.com/286822 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Corentin Wallez <cwallez@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>