tweak trackpad variables

Add static const and move them below in order to group the keyboard
options.

config.def.h

@@ -42,13 +42,13 @@ static const struct xkb_rule_names xkb_rules = {
 	*/
 };
 
-/* Trackpad */
-int tap_to_click = 1;
-int natural_scrolling = 1;
-
 static const int repeat_rate = 25;
 static const int repeat_delay = 600;
 
+/* Trackpad */
+static const int tap_to_click = 1;
+static const int natural_scrolling = 1;
+
 #define MODKEY WLR_MODIFIER_ALT
 #define TAGKEYS(KEY,SKEY,TAG) \
 	{ MODKEY,                    KEY,            view,            {.ui = 1 << TAG} }, \