intel/genxml: write a space before the '/>` closing tag

ElementTree.write will do this, and we want to minimize the diff when we
switch from our own writer to the builtin one.

Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18955>

src/intel/genxml/gen_sort_tags.py

@@ -107,7 +107,7 @@ def print_node(f: typing.TextIO, offset: int, node: et.Element) -> None:
             print_node(f, offset + 1, c)
         f.write('{0}</{1}>\n'.format(spaces, node.tag))
     else:
-        f.write('/>\n')
+        f.write(' />\n')
 
 
 def node_validator(old: et.Element, new: et.Element) -> bool: