toolchain-external: Add CodeSourcery Nios-II 2014.05

This new toolchain release fixes a number of issues found with the previous
one. In particular, the issues with fallocate64, prlimit64 and the
ill-installed linux headers seem to be fixed now.

Therefore, there's not need to sanitize the headers for this toolchain and some
packages should now build fine (e.g. fio).

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>