Meson: Align assert/check options with GLib

meson.build

@@ -98,7 +98,7 @@ if gst_version_is_dev
   add_project_arguments('-DG_DISABLE_DEPRECATED', language: 'c')
 endif
 
-if get_option('optimization') in ['2', '3', 's']
+if not get_option('debug') and get_option('optimization') in ['2', '3', 's']
   message('Disabling GLib cast checks')
   add_project_arguments('-DG_DISABLE_CAST_CHECKS', language: 'c')
 endif