Cache: fixed caching of intercepted errors (ticket #1382). When caching intercepted errors, previous behaviour was to use proxy_cache_valid times specified, regardless of various cache control headers present in the response. Fix is to check u->cacheable and use u->cache->valid_sec as set by various cache control response headers, similar to how we do this in the normal caching code path.

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


have=NGX_SUPPRESS_WARN . auto/have

have=NGX_SMP . auto/have