These functions are required to tell the driver that the memory object
is dedicated memory. This is required for AMD drivers on Linux.

Bug: chromium:1049218
Change-Id: I17d69cde5e6308791dc90784f4d6e348503a6ed6
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2110051Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>