Bug 6027 - Can't start karaf using symbolic link

Bug 6027 - Can't start karaf using symbolic link

When executing the karaf script, it gets the DIRNAME based on $0
which is the path used to start the script. This DIRNAME is then
used to set the KARAF_HOME and multiple other KARAF_* evn variables.

Using a symbolic link, you would have, for instance, usr/bin/karaf
redirecting to /opt/opendaylight/bin/karaf.
So $0 would be usr/bin and not /opt/opendaylight/bin so the locateHome
function isn't setting the right path for the KARAF_HOME.

This ends up failing to start ODL with following ERROR:
Error: Could not find or load main class org.apache.karaf.main.Main

see:
https://github.com/opendaylight/controller/blob/master/karaf/opendaylight-karaf-resources/src/main/resources/bin/karaf#l114l126

Change-Id: I36eff657972768de7d7b90f6563addfc3dd96c0f
Signed-off-by: Alexis de Talhouët <adetalhouet@inocybe.com>
Co-Authored-By: Michael Vorburger <vorburger@redhat.com>