Cache: reset c->body_start when reading a variant on Vary mismatch. Previously, a variant not present in shared memory and stored on disk using a secondary key was read using c->body_start from a variant stored with a main key. This could result in critical errors "cache file .. has too long header".

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


cat << END >> $NGX_AUTO_HEADERS_H

#ifndef $have
#define $have  1
#endif

END