When you use LTIB to build the kernel, any file will be placed into <ltib>/rootfs
That´s why you don´t see the file you want into your ubuntu rootfs.
Sorry, I don´t understand. Do you want to see gcc in ubuntu on your board? Or in ubuntu on your PC?
If you want it in ubuntu, please sudo apt-get install gcc (and it will take the properly gcc binary for your arch)
Do you really need the module? It cannot be built in?