Begin to require libosmocore and libosmovty

We are not too specific about the version yet
gtp: Move to using LOGP for logging GTP packages

Make libgtp depend on libosmocore and use the generic logging
infrastructure for it.
gtp: Kill unused and non public method
gtp: Make these regions runtime debuggable
syserr: Remove unused error packet logging code
logging: Switch to using libosmocore logging for all the code
ggsn: Be able to set the log level for the text file

Fixes: SYS#599
ggsn: Remove unused dump/logging method
ggsn: Move printf to DEBUGP statements in the ggsn as well

The specific log statements are not great yet but at least they
will end up in the log file. In the future everything should be
related to the IMSI or at least the tunnel id.