mcrypt is not required, but it's recommended to increase file encryption
performance. We're adding it to info.xml just to simplify abuild (all app
dependencies can be read in info.xml).

diff --git a/apps/encryption/appinfo/info.xml b/apps/encryption/appinfo/info.xml
index db4309c..4c43c09 100644
--- a/apps/encryption/appinfo/info.xml
+++ b/apps/encryption/appinfo/info.xml
@@ -31,6 +31,7 @@
 
 	<dependencies>
 		<lib>openssl</lib>
+		<lib>mcrypt</lib>
 		<nextcloud min-version="15" max-version="15" />
 	</dependencies>