tcsh: fix abort in cleanup_until(), caused by internal xgetpass()

The xgetpass() function pushes a cleanup entry for &osa, but then
attempts to flush the stack until an entry matching &sa. The two
object pointers do not match, so the stack is popped too much,
and then cleanup_until calls abort() when it unexpectedly hits
the bottom of the cleanup stack.

Reported by: Paul B. Mahol, onemda at gmail.com,

		Pietro Cerutti, gahr at gahr.ch

PR: bin/124191
Reviewed by: mp, kris
MFC after: 2 days