Since ngx_ff_module.c was derived from nginx_ofp's ngx_ofp_module.c, but
according to #42, nginx_ofp's ngx_ofp_module.c may be derived from
opendp/dpdk-nginx's ans_module.c and nginx_ofp didn't have a license, so
add opendp/dpdk-nginx's license.
The newer version of libcrypto will invoke read and close function when
dl_init, the real address of read/close function can’t be determined in
compilation phase and libcrypto will seek read/close symbol in ELF
files and other libraries. However nginx_fstack redefined these two
functions, this causes these symbols to be found in nginx_fstack. But the real read/close function is NULL before ff_mod_init, this leads to crash.
Changes:
1.if real_close is NULL, assign it with the address of close function in Glibc.
2.remove unnecessary read/readv/write.
logwang