vrend: Check if texture can be multisampled

v2: Check function availability
v3: Isolate function availability check to a variable (Gert Wollny)
v4: Use util_format_name and add a utility function (Gert Wollny)
v5: Move variables to narrower scopes (Gert Wollny)

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Part-of: <https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/715>
5 files changed