src/sulogin.c: Remove 'static' from local variable, but keep initialization

src/sulogin.c: Remove 'static' from local variable, but keep initialization

We don't need 'static', because it's in main(), which is only called
once.  However, we will need initialization as if it were 'static', so
use ={} to initialize it.  This will allow freeing the pointers before
they have been allocated.

Cc: Samanta Navarro <ferivoz@riseup.net>
Suggested-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>