libevent: add hash file

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libevent/libevent.hash

@@ -0,0 +1,2 @@
+# Locally calculated after checking pgp signature
+sha256	22a530a8a5ba1cb9c080cba033206b17dacd21437762155c6d30ee6469f574f5	libevent-2.0.21-stable.tar.gz