rockspecs.lua: fix a misnamed variable
rockspecs.lua: fix a misnamed variable

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