Upstream: fixed X-Accel-Expires/Cache-Control/Expires handling. Previously, if caching was disabled due to Expires in the past, nginx failed to cache the response even if it was cacheable as per subsequently parsed Cache-Control header (ticket #964). Similarly, if caching was disabled due to Expires in the past, "Cache-Control: no-cache" or "Cache-Control: max-age=0", caching was not used if it was cacheable as per subsequently parsed X-Accel-Expires header. Fix is to avoid disabling caching immediately after parsing Expires in the past or Cache-Control, but rather set flags which are later checked by ngx_http_upstream_process_headers() (and cleared by "Cache-Control: max-age" and X-Accel-Expires). Additionally, now X-Accel-Expires does not prevent parsing of cache control extensions, notably stale-while-revalidate and stale-if-error. This ensures that order of the X-Accel-Expires and Cache-Control headers is not important. Prodded by Vadim Fedorenko and Yugo Horie.

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


if [ $PCRE != NONE -a $PCRE != NO -a $PCRE != YES ]; then
    . auto/lib/pcre/make
fi

if [ $OPENSSL != NONE -a $OPENSSL != NO -a $OPENSSL != YES ]; then
    . auto/lib/openssl/make
fi

if [ $ZLIB != NONE -a $ZLIB != NO -a $ZLIB != YES ]; then
    . auto/lib/zlib/make
fi

if [ $NGX_LIBATOMIC != NO -a $NGX_LIBATOMIC != YES ]; then
    . auto/lib/libatomic/make
fi

if [ $USE_PERL != NO ]; then
    . auto/lib/perl/make
fi