Use GSList for buffer entries

src/ui/window.h

@@ -54,7 +54,7 @@ typedef enum {
 typedef struct prof_win_t {
     char *from;
     WINDOW *win;
-    ProfBuff *buffer;
+    ProfBuff buffer;
     win_type_t type;
     gboolean is_otr;
     gboolean is_trusted;