v3d: Introduce a DRM shim for calling out to the simulator.

The goal is to enable testing of parts of drivers without depending on any
particular kernel version or hardware being present.

Simply set LD_PRELOAD=$PREFIX/lib/libv3d_drm_shim.so in your environment,
and we'll fake a /dev/dri/renderD128 (or whatever the next available node
is) using v3dv3.  That node can then be used with the surfaceless or gbm
EGL platforms.

Acked-by: Iago Toral Quiroga <itoral@igalia.com>

meson.build

@@ -55,7 +55,16 @@ with_osmesa = get_option('osmesa')
 with_swr_arches = get_option('swr-arches')
 with_tools = get_option('tools')
 if with_tools.contains('all')
-  with_tools = ['etnaviv', 'freedreno', 'glsl', 'intel', 'nir', 'nouveau', 'xvmc']
+  with_tools = [
+    'drm-shim',
+    'etnaviv',
+    'freedreno',
+    'glsl',
+    'intel',
+    'nir',
+    'nouveau',
+    'xvmc',
+  ]
 endif
 
 dri_drivers_path = get_option('dri-drivers-path')