Can't install via luarocks

Nobody has claimed this yet.

It resolves all dependecies except luabitop:

```
lua-websockets$ sudo luarocks make rockspecs/lua-websockets-scm-1.rockspec

Missing dependencies for lua-websockets:
luabitop

Using https://luarocks.org/luabitop-1.0.2-1.src.rock... switching to 'build' mode
gcc -O2 -fPIC -I/usr/local/include -c bit.c -o bit.o
bit.c: In function ‘barg’:
bit.c:83:2: error: #error "Unknown number type, check LUA_NUMBER_* in luaconf.h"
#error "Unknown number type, check LUA_NUMBER_* in luaconf.h"
^

Error: Failed installing dependency: https://luarocks.org/luabitop-1.0.2-1.src.rock - Build error: Failed compiling object bit.o
```

```

$ lua -v
Lua 5.3.3 Copyright (C) 1994-2016 Lua.org, PUC-Rio
$ luarocks --version
/usr/local/lib/luarocks/rocks/luarocks/2.3.0-1/bin/luarocks 2.3.0
LuaRocks main command-line interface

```

Reproduce the reported command with Lua 5.3.3 and LuaRocks 2.3.0, then inspect rockspecs/lua-websockets-scm-1.rockspec and the luabitop failure in bit.c. Done means the dependency installs successfully and lua-websockets can be installed through the shown luarocks command.

Written by the indexing model from the issue text.