[Backport] Add config.x_vt option

Signed-off-by: AnErrupTion <anerruption@disroot.org>

res/config.ini

@@ -354,6 +354,11 @@ waylandsessions = $PREFIX_DIRECTORY/share/wayland-sessions
 # Xorg server command
 x_cmd = $PREFIX_DIRECTORY/bin/X
 
+# Xorg virtual terminal number
+# Mostly useful for FreeBSD where choosing the current TTY causes issues
+# If null, the current TTY will be chosen
+x_vt = null
+
 # Xorg xauthority edition tool
 xauth_cmd = $PREFIX_DIRECTORY/bin/xauth