luajit: bump to version 2.0.3

Signed-off-by: Francois Perrad <francois.perrad@gadz.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
luajit: add host variant
luainterpreter: add host variant
luarocks: allow to work with host-luainterpreter

when we embed luajit on target, we use luarocks with host-luajit instead of host-lua
lua-iconv: new package