Windows: Ensure core windows are fully initialised.

frontends/windows/cookies.c

@@ -136,7 +136,7 @@ static nserror nsw32_cookie_init(HINSTANCE hInstance)
 		return NSERROR_OK;
 	}
 
-	ncwin = malloc(sizeof(struct nsw32_cookie_window));
+	ncwin = calloc(1, sizeof(*ncwin));
 	if (ncwin == NULL) {
 		return NSERROR_NOMEM;
 	}

frontends/windows/global_history.c

@@ -126,7 +126,7 @@ static nserror nsw32_global_history_init(HINSTANCE hInstance)
 		return NSERROR_OK;
 	}
 
-	ncwin = malloc(sizeof(struct nsw32_global_history_window));
+	ncwin = calloc(1, sizeof(*ncwin));
 	if (ncwin == NULL) {
 		return NSERROR_NOMEM;
 	}

frontends/windows/hotlist.c

@@ -130,7 +130,7 @@ static nserror nsw32_hotlist_init(HINSTANCE hInstance)
 		return NSERROR_OK;
 	}
 
-	ncwin = malloc(sizeof(struct nsw32_hotlist_window));
+	ncwin = calloc(1, sizeof(*ncwin));
 	if (ncwin == NULL) {
 		return NSERROR_NOMEM;
 	}

frontends/windows/local_history.c

@@ -143,7 +143,7 @@ nsw32_local_history_init(HINSTANCE hInstance,
 		return res;
 	}
 
-	ncwin = malloc(sizeof(struct nsw32_local_history_window));
+	ncwin = calloc(1, sizeof(*ncwin));
 	if (ncwin == NULL) {
 		return NSERROR_NOMEM;
 	}