The recent lua 5.3 addition broke this.

Signed-off-by: Rosen Penev <rosenp@gmail.com>

LUAROCKS_UNAME_S/LUAROCKS_UNAME_M were being set automatically to host’s architecture and system/kernel name (e.g.. x86 and Darwin for the macOS)
The variables can now be supplied to configure via the supplied patch.
They are currently _S being hardcoded to “Linux” and _M set to the target architecture in the MakeFile.

Signed-off-by: David Thornley <david.thornley@touchstargroup.com>

Signed-off-by: Amr Hassan <amr.hassan@gmail.com>