Initialize prompt buffers in the configuration menus

malloc() does not make sure that the buffer is initialized to contain
all zeros. Initialize the buffer with the empty string.

Reported-by: Håkan Jerning <jerning@home.se>
Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/custom.c

@@ -689,7 +689,10 @@ static void general_option_edit(int i)
 	const char *periodic_save_str =
 	    _("Enter the delay, in minutes, between automatic saves (0 to disable) ");
 	int val;
-	char *buf = malloc(BUFSIZ);
+	char *buf;
+
+	buf = mem_malloc(BUFSIZ);
+	buf[0] = '\0';
 
 	switch (i) {
 	case 0:

src/notify.c

@@ -693,6 +693,7 @@ static void config_option_edit(int i)
 	const char *cmd_str = _("Enter the notification command ");
 
 	buf = mem_malloc(BUFSIZ);
+	buf[0] = '\0';
 
 	switch (i) {
 	case 0: