* common/sysutils.c (gnupg_rename_file): Factor out the wait function
to ...
(w32_wait_when_sharing_violation): New.
(w32_remove): New.
(gnupg_remove_ext): New.
(gnupg_remove): Now a wrapper arounf gnupg_remove_ext.
(gnupg_rename_file) [W32]: Use 32_remove with indefinite wait for
sharing violation.