gmem: Only evaluate pointer argument to g_clear_pointer() once
The new typeof() macro version of g_clear_pointer() was evaluating its pointer argument more than once, meaning any side effects would be evaluated multiple times.
The existing (other) macro version of g_clear_pointer() was evaluating its argument exactly once. This mismatch could have confused people or lead to subtle bugs.
See #1494 (closed).
Signed-off-by: Philip Withnall withnall@endlessm.com
Ideally this should go into 2.58 before the new g_clear_pointer() version makes it into a stable release.