update LuaRocks rocks to ignore

There are multiple compiled rock types `*.src.rock` is just one.

* `*.src.rock` denotes a source archive
* `*.all.rock` is for all platforms (pure Lua)
* platform specific ones like `*.win32.rock` (contains binaries)

see https://github.com/luarocks/luarocks/wiki/Types-of-rocks

Lua.gitignore

@@ -2,7 +2,7 @@
 luac.out
 
 # luarocks build files
-*.src.rock
+*.rock
 *.zip
 *.tar.gz