Fix createPluginJar.sh after submoduling

(Now only builds plugins that have been updated, again)

Change-Id: Icd549ebb2d5ed31a85f3ef64ac640cbdff44354c
Reviewed-on: http://gerrit.dmdirc.com/285
Reviewed-by: Gregory Holmes <greboid@dmdirc.com>
Tested-by: Gregory Holmes <greboid@dmdirc.com>

createPluginJar.sh

 pluginname=${1}
 foldername=${pluginname//.//}
 
-newer=`find src/${foldername} -type f -newer ${srcdir}/plugins/${2}.jar 2>&1 | wc -l`
+newer=`find ${srcdir}/src/${foldername} -type f -newer ${destdir}/plugins/${2}.jar 2>&1 | wc -l`
 
 if [ $newer -eq 0 ]; then
 	echo "${2}.jar appears to be up-to-date";