Allow building without X11 support

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

src/config/Lang.zig

@@ -45,6 +45,7 @@ insert: []const u8 = "insert",
 login: []const u8 = "login:",
 logout: []const u8 = "logged out",
 normal: []const u8 = "normal",
+no_x11_support: []const u8 = "x11 support disabled at compile-time",
 numlock: []const u8 = "numlock",
 other: []const u8 = "other",
 password: []const u8 = "password:",