libevent: Fix 64-bit build

The arc4random_addrandom() function has been removed from 64-bit
Android libc.

packages/libevent/evutil_rand.c.patch

@@ -0,0 +1,19 @@
+diff -u -r ../libevent-2.0.22-stable/evutil_rand.c ./evutil_rand.c
+--- ../libevent-2.0.22-stable/evutil_rand.c	2013-11-01 14:18:57.000000000 -0400
++++ ./evutil_rand.c	2016-01-03 20:05:10.168762009 -0500
+@@ -171,10 +171,15 @@
+ 	ev_arc4random_buf(buf, n);
+ }
+ 
++#ifndef __ANDROID__
++/* The arc4random_addrandom() has been removed from 64-bit Android libc,
++   see https://bugzilla.mozilla.org/show_bug.cgi?id=931354 for motivation
++   about just removing this function completely. */
+ void
+ evutil_secure_rng_add_bytes(const char *buf, size_t n)
+ {
+ 	arc4random_addrandom((unsigned char*)buf,
+ 	    n>(size_t)INT_MAX ? INT_MAX : (int)n);
+ }
++#endif
+