The search was initiated with base == 0, which returns NULL immediately
if MEM_TOP_DOWN is not used. Use address_space_start instead.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=47974Signed-off-by: Rémi Bernon <rbernon@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>