qemu-guest.nix: Disable rngd

This gets rid of a zillion "rngd[N]: read error" messages during boot.

Changed files
+2
nixos
modules
profiles
+2
nixos/modules/profiles/qemu-guest.nix
···
# to the *boot time* of the host).
hwclock -s
'';
+
+
security.rngd.enable = false;
}