meson: remove deprecated dri-drivers option

This was deprecated in cdde031ac2 ("classic/i965: Remove driver"),
which is almost two years ago, and many major releases ago. Nobody
should be using this any more. Let's remove it.

Reviewed-by: David Heidelberg <david.heidelberg@collabora.com>
Reviewed-by: Eric Engestrom <eric@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20905>

meson.build

@@ -131,11 +131,6 @@ if with_freedreno_kgsl
   system_has_kms_drm = false
 endif
 
-dri_drivers = get_option('dri-drivers')
-if dri_drivers.length() != 0
-  error('Mesa\'s main branch no longer has any "classic" drivers, use the "amber" branch instead.')
-endif
-
 gallium_drivers = get_option('gallium-drivers')
 if gallium_drivers.contains('auto')
   if system_has_kms_drm

meson_options.txt

@@ -55,11 +55,6 @@ option(
   type : 'feature',
   description : 'enable support for dri3'
 )
-option(
-  'dri-drivers',
-  type : 'array',
-  description : 'DEPRECATED: List of dri drivers to build. If this is set to auto all drivers applicable to the target OS/architecture will be built'
-)
 option(
   'dri-drivers-path',
   type : 'string',