virgl: Always enable emulated BGRA and swizzling unless specifically told not to

The emulation is turned on by default only for GLES hosts when the
host does not support the BGRA/RGBA external/internal format
combination.

This can be turned off by setting VIRGL_DEBUG=noemubgra,nobgraswz
environment variable.

Signed-off-by: Rohan Garg <rohan.garg@collabora.com>
Reviewed-by: Gert Wollny <gert.wollny@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6847>
4 files changed