OSSL_HTTP_get(): Reset redirection_url in each iteration

Also remove some dead assignments.

Obtained from: openssl (e78c8b791c0e03e750ef7196bc7bfee8e5bd00a0)

MFC after: 2 weeks
Requested by: Phillip Sabatino
Sponsored by: Dell, Inc.

(cherry picked from commit 18378ef11a0a5a8fb6c62761b1a20c23c12a4aa6)