meson: Error building kmsro-required driver without kmsro
As I discovered while accidentally setting -Dgallium-drivers=panfrost,
nothing in the build system fails with the combination of "driver
requiring kmsro" and "no kmsro". Rather an inscrutable run time failure
is raised that gives no insight into the missing dependency. So let's
detect this case at build-time.
It's worth noting we can't simply set kmsro internally based on the
driver list without changing behaviour, as it is possible to build
freedreno with or without kmsro support. Rob and Eric says it's fine, so let's do that.
Signed-off-by: Alyssa Rosenzweig alyssa.rosenzweig@collabora.com