wins_show(): Fix size of the slave window array

The slave window array was just big enough to hold a single element,
whereas two elements are written/accessed. Fix this off-by-one error in
the array declaration.

Note that this messed up the panel layout when using clang as a
compiler.

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

src/wins.c

@@ -373,7 +373,7 @@ void wins_show(WINDOW * win, const char *label)
 void wins_get_config(void)
 {
   enum win win_master;
-  enum win win_slave[1];
+  enum win win_slave[2];
   unsigned master_is_left;
 
   /* Get the screen configuration */