tmux: Put some parts in version >= 3.3 checks

Ubuntu 22.04 is shipped with 3.2a... There might be more issues with
that version, but these were the ones I could find for now.

Tmux commits needed:
- c03b57465bdf/866117636e47 ("Add different command historys for
  different types of prompts ("command", "search" etc). From Anindya
  Mukherjee.") for `prompt-history-limit`
- e06a4e041c68 ("Set mouse_x and mouse_y on the status line, GitHub
  issue 2913.") for mouse_x in MouseDragEnd1StatusDefault binding
- 9f6164a05cc0 ("Make send-keys without any arguments send the key it is
  bound to (if any). GitHub issue 2904.") for `C-d`, `Enter` bindings

.config/tmux/tmux.conf

@@ -3,7 +3,9 @@ set -g mouse on
 set -g mode-keys vi
 set -g extended-keys always
 
-set -g prompt-history-limit 999999
+if -F "#{>=:#{version},3.3}" {
+	set -g prompt-history-limit 999999
+}
 set -g history-file "$XDG_DATA_HOME/tmux/tmux_history"
 run-shell 'mkdir -p "${XDG_DATA_HOME:-$HOME/.local/share}/tmux"'
 
@@ -168,11 +170,14 @@ bind -r P swap-window -d -t :-1
 bind -n MouseDrag1Status swap-window -d -t=
 
 # TODO: do nothing on drags that don't start on a window name
-bind -n MouseDragEnd1StatusDefault {
-	if -F "#{e|>|f|0:#{mouse_x},#{e|/|f:#{window_width},2}}" {
-		run-shell "tmux move-window -at #{last_window_index}"
-	} {
-		move-window -t0
+# NOTE: mouse_{x,y} were not set in status line before 3.3
+if -F "#{>=:#{version},3.3}" {
+	bind -n MouseDragEnd1StatusDefault {
+		if -F "#{e|>|f|0:#{mouse_x},#{e|/|f:#{window_width},2}}" {
+			run-shell "tmux move-window -at #{last_window_index}"
+		} {
+			move-window -t0
+		}
 	}
 }
 
@@ -327,8 +332,14 @@ bind S set -w synchronize-panes
 
 # Require confirmation before killing a pane
 set -g remain-on-exit on
-bind -n C-d if -F "#{pane_dead}" { kill-pane } { send }
-bind -n Enter if -F "#{pane_dead}" { respawn-pane } { send }
+if -F "#{>=:#{version},3.3}" {
+	bind -n C-d if -F "#{pane_dead}" { kill-pane } { send }
+	bind -n Enter if -F "#{pane_dead}" { respawn-pane } { send }
+} {
+	# omitting the key argument was introduced in 3.3
+	bind -n C-d if -F "#{pane_dead}" { kill-pane } { send C-d }
+	bind -n Enter if -F "#{pane_dead}" { respawn-pane } { send Enter }
+}
 
 # Change installation location of plugins
 setenv -g TMUX_PLUGIN_MANAGER_PATH "$XDG_CONFIG_HOME/tmux/plugins/"