xcursor: use internal_config

Removes a project argument, improves escaping.

xcursor/meson.build

@@ -2,8 +2,7 @@ icondir = get_option('icon_directory')
 if icondir == ''
 	icondir = get_option('prefix') / get_option('datadir') / 'icons'
 endif
-
-add_project_arguments('-DICONDIR="@0@"'.format(icondir), language : 'c')
+internal_config.set_quoted('ICONDIR', icondir)
 
 wlr_files += files(
 	'wlr_xcursor.c',

xcursor/xcursor.c

@@ -28,6 +28,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include "config.h"
 #include "xcursor/xcursor.h"
 
 /*