Update to build scripts

[Chris]

Two bugs that came to light with the build script v4 and have been fixed:

* crosstool was rejecting gcc 4.1. Using gcc 4.1 seems to generate a working cross compiler so it has been modified to allow gcc 4.1. Thanks to carsten for working on that.
* The kernel is built with a different version string to the one Hauppauge use meaning that insmod has to be given the -f switch to load the modules. -f was missing from the insmods script in the NFS root development file system tar. Fixed.