Auditd seems to build its own libev if the library is not already present;
otherwise it uses the system-installed library. This adds libev as a
dependency to ensure a consistent build.

Signed-off-by: W. Michael Petullo <mike@flyn.org>

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
[strip library after adding it to openwrt repository]
Signed-off-by: W. Michael Petullo <mike@flyn.org>