ProgramGL: Make sure the binary vector does not read out of bounds. By sizing the vector to at least one element, it is not possible to pass invalid pointers to the driver or binary stream even if the binary is zero-sized. BUG=angleproject:2257 Change-Id: Ie0e42bff1192207e0e069934b03dfd49e8d34824 Reviewed-on: https://chromium-review.googlesource.com/779739 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Geoff Lang <geofflang@chromium.org>