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).

--- 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="14" max-version="14" />
 	</dependencies>