meson: replace with_*dri with with_dri_platform

This fixes the windows and macos stubs to be consistent with the *nix
path.

Signed-off-by: Dylan Baker <dylanx.c.baker@intel.com>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>

meson.build

@@ -52,10 +52,6 @@ if get_option('texture-float')
   message('WARNING: Floating-point texture enabled. Please consult docs/patents.txt and your lawyer before building mesa.')
 endif
 
-# XXX: yeah, do these
-with_appledri = false
-with_windowsdri = false
-
 dri_drivers_path = get_option('dri-drivers-path')
 if dri_drivers_path == ''
   dri_drivers_path = join_paths(get_option('libdir'), 'dri')