Install in ubuntu on ARM is missing resty.random

Following install process get this error on start:

```
init_by_lua error: /usr/local/share/lua/5.1/resty/auto-ssl/init.lua:1: module 'resty.random' not found:
no field package.preload['resty.random']
no file './resty/random.lua'
no file '/usr/share/luajit-2.0.4/resty/random.lua'
no file '/usr/local/share/lua/5.1/resty/random.lua'
no file '/usr/local/share/lua/5.1/resty/random/init.lua'
no file '/usr/share/lua/5.1/resty/random.lua'
no file '/usr/share/lua/5.1/resty/random/init.lua'
no file './resty/random.so'
no file '/usr/local/lib/lua/5.1/resty/random.so'
no file '/usr/lib/arm-linux-gnueabihf/lua/5.1/resty/random.so'
no file '/usr/local/lib/lua/5.1/loadall.so'
no file './resty.so'
no file '/usr/local/lib/lua/5.1/resty.so'
no file '/usr/lib/arm-linux-gnueabihf/lua/5.1/resty.so'
no file '/usr/local/lib/lua/5.1/loadall.so'
stack traceback:
[C]: in function 'require'
/usr/local/share/lua/5.1/resty/auto-ssl/init.lua:1: in main chunk
[C]: in function 'require'
/usr/local/share/lua/5.1/resty/auto-ssl.lua:59: in function 'init'
init_by_lua:11: in main chunk
```

Reproduce the installation on Ubuntu ARM and start by tracing the require from /usr/local/share/lua/5.1/resty/auto-ssl/init.lua, then inspect the startup path through resty/auto-ssl.lua and init_by_lua. Done means the installation provides resty.random and OpenResty starts without the reported module-not-found error.

Written by the indexing model from the issue text.