Linux: Enable udev support by default

This has been enabled for years in official binaries, and users making custom builds
may end up not enabling it unknowingly, so it's best if we default to the same as
what official builds do.

The original reason for having it opt-in was likely the addition of a dependency on
libudev, but that should be fairly ubiquitous by now.

(cherry picked from commit e8b69fccbe3740e591f27cb325a12afb013bebdd)

platform/x11/detect.py

@@ -71,7 +71,7 @@ def get_opts():
         BoolVariable("use_lsan", "Use LLVM/GCC compiler leak sanitizer (LSAN))", False),
         BoolVariable("use_tsan", "Use LLVM/GCC compiler thread sanitizer (TSAN))", False),
         BoolVariable("pulseaudio", "Detect and use PulseAudio", True),
-        BoolVariable("udev", "Use udev for gamepad connection callbacks", False),
+        BoolVariable("udev", "Use udev for gamepad connection callbacks", True),
         EnumVariable("debug_symbols", "Add debugging symbols to release/release_debug builds", "yes", ("yes", "no")),
         BoolVariable("separate_debug_symbols", "Create a separate file containing debugging symbols", False),
         BoolVariable("touch", "Enable touch events", True),