Do not cast unused return values to void

A small style fix that removes all remaining "(void)" casts. Using these
isn't encouraged in GNU coding guidelines and doesn't serve a certain
purpose, except for satisfying a few static code analysis tools. We
already nuked some of these in previous patches, but this semantic patch
should fix what's left:

    @@
    identifier func;
    @@

    - (void)func (
    + func (
    ...);

Long lines were re-formatted manually.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/vars.c

@@ -129,7 +129,7 @@ vars_init (struct conf *conf)
   conf->periodic_save = 0;
   conf->skip_system_dialogs = 0;
   conf->skip_progress_bar = 0;
-  (void)strncpy (conf->output_datefmt, "%D", 3);
+  strncpy (conf->output_datefmt, "%D", 3);
   conf->input_datefmt = 1;
 
   /* Default external editor and pager */