When available use /dev/urandom to get the random seem. This will lower the probability
of collisions.

On other systems it will fallback to the old methods.

Passes bootstrap + testsuite on x86_64. Ok?

gcc/:

2011-09-26   Andi Kleen <ak@linux.intel.com>

	* toplev.c (init_local_tick): Try reading random seed from /dev/urandom

From-SVN: r179348