Add libevent 2.1.5-beta tarball.

Change-Id: I24b036112e63696c063895d0ed94c87aaead2584
diff --git a/libevent-2.1.5-beta.tar.gz b/libevent-2.1.5-beta.tar.gz
new file mode 100644
index 0000000..fb89f2f
--- /dev/null
+++ b/libevent-2.1.5-beta.tar.gz
Binary files differ