meson: split subdir for virtio/vdrm and virtio/vulkan

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35723>

meson.build

@@ -288,6 +288,8 @@ if freedreno_kmds.length() != 0 and freedreno_kmds != [ 'msm' ] and with_freedre
 endif
 
 with_vdrm = [
+  with_gallium_virgl,
+  with_virtio_vk,
   with_amdgpu_virtio,
   freedreno_kmds.contains('virtio'),
   with_gallium_asahi,

src/meson.build

@@ -70,8 +70,11 @@ endif
 if with_any_intel
   subdir('intel')
 endif
-if with_vdrm or with_gallium_virgl or with_virtio_vk
+if with_virtio_vk
-  subdir('virtio')
+  subdir('virtio/vulkan')
+endif
+if with_vdrm
+  subdir('virtio/vdrm')
 endif
 if with_gallium_radeonsi or with_amd_vk or with_gallium_r300 or with_gallium_r600
   subdir('amd')

src/virtio/meson.build

@@ -1,9 +0,0 @@
-# Copyright © 2017 Intel Corporation
-# SPDX-License-Identifier: MIT
-
-inc_virtio_vdrm = include_directories('./vdrm')
-
-if with_virtio_vk
-  subdir('vulkan')
-endif
-subdir('vdrm')

src/virtio/vdrm/meson.build

@@ -1,6 +1,8 @@
 # Copyright 2023 Google LLC
 # SPDX-License-Identifier: MIT
 
+inc_virtio_vdrm = include_directories('.')
+
 libvdrm = static_library(
   'libvdrm',
   [