Merge important fixes to levent

commit b8f59807ceb66ad0408182fd0b70a971137ad4ae
Author: Frank Denis <github@pureftpd.org>
Date:   Sat Jul 20 14:02:49 2013 -0700

    libevent/win32_dealloc() : fix sizeof(pointer) vs sizeof(*pointer)

commit 6e4969614723a46061d6a98162480de209fd03a0
Author: Nick Mathewson <nickm@torproject.org>
Date:   Mon Jun 10 10:38:12 2013 -0400

    Document that arc4random is not a great cryptographic PRNG.

commit e35b540832825437827addeb7ecd04c3e14d81bb
Author: Nick Mathewson <nickm@torproject.org>
Date:   Mon Jun 10 10:33:56 2013 -0400

    When we seed from /proc/sys/kernel/random/uuid, count it as success

    Found by Joseph Spadavecchia

commit f8d7df859148905195054ed1255f46970039a34f
Author: Azat Khuzhin <a3at.mail@gmail.com>
Date:   Sat May 11 03:53:11 2013 +0400

    Fix SEGFAULT after evdns_base_resume if no nameservers installed.

    If there is no nameservers installed, using
    evdns_base_nameserver_ip_add(), than evdns_base_resume() will SEGFAULT,
    because of NULL dereference in evdns_requests_pump_waiting_queue()

    Conflicts:
    	evdns.c

commit e826f19e05b65ffea1a1699160cee7516962c939
Author: Nick Mathewson <nickm@torproject.org>
Date:   Wed May 29 13:30:56 2013 -0400

    Use windows vsnprintf fixup logic on all windows environments

    Previously I'd relied on mingw to provide a vsnprintf with a
    conformant return value.  But it appears that some mingw
    environments don't do that.

commit 5c710c03625d620811cf6b97a37b666e0424e88e
Author: Belobrov Andrey <belobrovap@infotecs.ru>
Date:   Mon May 6 18:15:03 2013 +0400

    Checking request nameserver for NULL, before using it.