use /dev/urandom instead of /dev/random to seed the random generator.

The problem is that /dev/random can hang on Linux (due to lack of entropy)
in which case rootd and proofd hang during authentication. With urandom
there is no such problem since in case of lack of entropy it will fall
back on a software algorithm (it will never hang). This was observed in
the ALICE Data Challenge.


git-svn-id: http://root.cern.ch/svn/root/trunk@8080 27541ba8-7e3a-0410-8455-c3a389f83636