Add signals support.
Add signals support.

zevv/luaposix,luaposix/luaposix,rrthomas/luaposix,zevv/luaposix,ardje/luaposix,rrthomas/luaposix,jimmyharris/luaposix,ardje/luaposix,snegovick/luaposix,snegovick/luaposix,jimmyharris/luaposix