binfmt_elf.c: use get_random_int() to fix entropy depleting (Jeff Liu )

See http://lkml.indiana.edu/hypermail/linux/kernel/1211.1/03767.html for details.
random: remove warning
random: prevent add_input from doing anything
random: entropy tweaks are all the rage nowadays

use non-blocking pool for all

http://lwn.net/Articles/489734/