Build ngx_mruby dynamic module for CentOS.
Just execute make.
$ make
And, ngx_mruby (ngx_http_mruby_module.so) and depended NDK (ndk_http_module.so) module files are created in your local dist directory.
$ ls ./dist
ndk_http_module.so ngx_http_mruby_module.so
You can specify versions of nginx and ngx_mruby with make arguments.
$ make NGINX_VERSION:=1.23.1 NGX_MRUBY_VERSION:=2.2.5
If you want to adjust build configuration, you can edit build_config.rb.
This file is used instead of build_config.rb bundled with ngx_mruby on build.