GDB transparent support process: improve the paused msg

Signed-off-by: Cleber Rosa <crosa@redhat.com>
GDB transparent support: deal with situation where inferior process finishes in GDB

Before Avocado is actually back into play and receivies information on how the
process actually finished. Because of the lack of information, we give that process
an exit status of 0.

A detailed message is given in the logs regarding the ideal use of avocado GDB
support and what actually happened during that test.

Signed-off-by: Cleber Rosa <crosa@redhat.com>