PROX: print panic message on screen

PROX: print panic message on screen

When PROX detects an error condition at startup, it calls PROX_PANIC
which prints an message before calling rte_panic to end the application.
If ncurses was already started, this results in the message being printed
in ncurses (and prox.log) then leaving ncurses; hence the message is usually
not visible to the user (until it open prox.log), giving the impression of an
unexpected crash.

With this fix, the error message is repeated after closing ncurses, hence the message
will be printed on stdout.
Note that it might also be printed twice on stdout if ncurses was not already started.

As part of this fix, prox.log is now properly closed.

Change-Id: If41875843f1a39bc715f4264b3992c3fa018394e
Signed-off-by: Xavier Simonart <xavier.simonart@intel.com>