package/rabbitmq-c: needs dynamic library

syslog-ng expects that rabbitmq-c is built with openssl support however
currently we're disabling openssl on rabbitmq-c in static build.

To fix this issue, add a dependency on dynamic library on rabbitmq-c and
its reverse dependencies (only BR2_PACKAGE_JANUS_GATEWAY_RABBITMQ as
php-amqp already depends on dynamic library)

Fixes:
 - http://autobuild.buildroot.org/results/fce91b98fb199a26ad5f5f726c9bdec4f9d64486



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>