bug#24628: GNUtls initialization adds 500ms to startup --- do we really need it just for the RNG?

[Daniel Colascione]

On my system, I noticed that the call to emacs_gnutls_global_init is 
adding 500ms to the time it takes to run emacs -Q -nw --batch --eval 
'(kill-emacs)'. We're not actually using GNUtls for anything but an RNG 
seed, and /dev/urandom is also up to the task.

I'm not sure what's making GNUtls so slow, except that it's talking to a 
process called credkit-service, which is using a lot of CPU time. It 
shouldn't matter though.

Can we go back to just using /dev/urandom directly?