meson: Convert platform to auto

This is necessary to support operating systems other than the *nix
family (excluding macOS). For Linux nothing has changed, the defaults
are still the same.

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

meson.build

@@ -198,6 +198,13 @@ with_platform_drm = false
 with_platform_surfaceless = false
 egl_native_platform = ''
 _platforms = get_option('platforms')
+if _platforms == 'auto'
+  if ['linux'].contains(host_machine.system())
+    _platforms = 'x11,wayland,drm,surfaceless'
+  else
+    error('Unknown OS, no platforms enabled. Patches gladly accepted to fix this.')
+  endif
+endif
 if _platforms != ''
   _split = _platforms.split(',')
   with_platform_android = _split.contains('android')

meson_options.txt

@@ -21,8 +21,8 @@
 option(
   'platforms',
   type : 'string',
-  value : 'x11,wayland,drm,surfaceless',
-  description : 'comma separated list of window systems to support. wayland, x11, surfaceless, drm, etc.'
+  value : 'auto',
+  description : 'comma separated list of window systems to support. If this is set to auto all platforms applicable to the OS will be enabled.'
 )
 option(
   'dri3',