Copy regex unnamed captures to cloned subrequests. Previously, unnamed regex captures matched in the parent request, were not available in a cloned subrequest. Now 3 fields related to unnamed captures are copied to a cloned subrequest: r->ncaptures, r->captures and r->captures_data. Since r->captures cannot be changed by either request after creating a clone, a new flag r->realloc_captures is introduced to force reallocation of r->captures. The issue was reported as a proxy_cache_background_update misbehavior in http://mailman.nginx.org/pipermail/nginx/2018-December/057251.html.

# 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