HID support on macOS

[rom1v]

#2632 added support for HID keyboards, using libusb. It is currently only supported on Linux (because it just works).

If someone knows how to make it work on macOS, your help is welcome.

You must enable the feature for all platforms:

diff --git a/app/meson.build b/app/meson.build
index 7f675035..ab035bf8 100644
--- a/app/meson.build
+++ b/app/meson.build
@@ -72,7 +72,7 @@ if v4l2_support
     src += [ 'src/v4l2_sink.c' ]
 endif
 
-usb_support = host_machine.system() == 'linux'
+usb_support = true
 if usb_support
     src += [
         'src/usb/aoa_hid.c',

Then, if you manage to make it wok, please submit a PR.

[rom1v]

Please test #3031.