allow symbol evutil_secure_rng_add_bytes (#578)

use arc4random_random where available or export empty symbol

packages/libevent/build.sh

@@ -1,7 +1,7 @@
 TERMUX_PKG_HOMEPAGE=http://libevent.org/
 TERMUX_PKG_DESCRIPTION="Library that provides asynchronous event notification"
 TERMUX_PKG_VERSION=2.0.22
-TERMUX_PKG_BUILD_REVISION=1
+TERMUX_PKG_BUILD_REVISION=2
 TERMUX_PKG_SRCURL=https://github.com/libevent/libevent/releases/download/release-${TERMUX_PKG_VERSION}-stable/libevent-${TERMUX_PKG_VERSION}-stable.tar.gz
 # Strip away libevent core, extra and openssl libraries until someone uses them
 TERMUX_PKG_RM_AFTER_INSTALL="bin/event_rpcgen.py lib/libevent_*"

packages/libevent/evutil_rand.c.patch

@@ -1,19 +0,0 @@
-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
- 

packages/libevent/evutil_secure_rng_add_bytes.patch

@@ -0,0 +1,26 @@
+Patch taken from https://gitweb.torproject.org/orbot.git/tree/external/libevent-patch-1
+For some reason arc4random_addrandom isn't present in 64-bit android archs. !
+
+--- ./configure.ac	2015-01-05 20:00:02.000000000 +0530
++++ ../configure.ac	2016-12-06 10:15:44.617028345 +0530
+@@ -290,7 +290,7 @@
+ 
+ dnl Checks for library functions.
+ AC_CHECK_FUNCS([gettimeofday vasprintf fcntl clock_gettime strtok_r strsep])
+-AC_CHECK_FUNCS([getnameinfo strlcpy inet_ntop inet_pton signal sigaction strtoll inet_aton pipe eventfd sendfile mmap splice arc4random arc4random_buf issetugid geteuid getegid getprotobynumber setenv unsetenv putenv sysctl])
++AC_CHECK_FUNCS([getnameinfo strlcpy inet_ntop inet_pton signal sigaction strtoll inet_aton pipe eventfd sendfile mmap splice arc4random arc4random_buf arc4random_addrandom issetugid geteuid getegid getprotobynumber setenv unsetenv putenv sysctl])
+ AC_CHECK_FUNCS([umask])
+ 
+ AC_CACHE_CHECK(
+--- ./evutil_rand.c	2013-11-01 23:48:57.000000000 +0530
++++ ../evutil_rand.c	2016-12-06 10:38:19.748912002 +0530
+@@ -174,7 +176,9 @@
+ void
+ evutil_secure_rng_add_bytes(const char *buf, size_t n)
+ {
++#ifdef _EVENT_HAVE_ARC4RANDOM_ADDRANDOM
+ 	arc4random_addrandom((unsigned char*)buf,
+ 	    n>(size_t)INT_MAX ? INT_MAX : (int)n);
++#endif
+ }
+