kerberos.c: Initialize random number generator on the server side so

kerberos.c: Initialize random number generator on the server side so
	that the encryption routines later on can use it.

	Fix bug in how we pick the challenge for the challenge/response
	mutual authentication.

forward.c: Move rd_cred and mk_cred to libkrb.a.  (Although we still
	need to fix the API!)

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@4658 dc483132-0cff-0310-8789-dd5450dbe970