Upstream: even better handling of invalid headers in cache files. When parsing of headers in a cache file fails, already parsed headers need to be cleared, and protocol state needs to be reinitialized. To do so, u->request_sent is now set to ensure ngx_http_upstream_reinit() will be called. This change complements improvements in 46ddff109e72.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


have=NGX_SUPPRESS_WARN . auto/have

have=NGX_SMP . auto/have