I tried to do the following
./configure --prefix=/home/tim/openresty --without-http_gzip_module --without-http_ssl_module
I got the error
./configure: error: SSL modules require the OpenSSL library.
You can either do not enable the modules, or install the OpenSSL library
into the system, or build the OpenSSL library statically from the source
with nginx by using --with-openssl=<path> option.
This is using version 1.13.6.1 of openresty on ubuntu.
I have worked round the problem by altering the "configure" script