Build on macOS with libusb support

Fixes #2774 <https://github.com/Genymobile/scrcpy/issues/2774>
PR #3031 <https://github.com/Genymobile/scrcpy/pull/3031>

BUILD.md

@@ -199,7 +199,7 @@ Install the packages with [Homebrew]:
 
 ```bash
 # runtime dependencies
-brew install sdl2 ffmpeg
+brew install sdl2 ffmpeg libusb
 
 # client build dependencies
 brew install pkg-config meson

app/meson.build

@@ -74,7 +74,7 @@ if v4l2_support
     src += [ 'src/v4l2_sink.c' ]
 endif
 
-usb_support = get_option('usb') and host_machine.system() == 'linux'
+usb_support = get_option('usb') and host_machine.system() != 'windows'
 if usb_support
     src += [
         'src/usb/aoa_hid.c',