veyron/lib/bluetooth: Fix build when -tags=veyronbluetooth is not specified
and/or building on non-linux.

Build for the veyron/services/proximity/lib package was failing with:
src/veyron/services/proximity/lib/bluetooth_scanner.go:30: s.device.StartScan undefined (type *bluetooth.Device has no field or method StartScan)
src/veyron/services/proximity/lib/bluetooth_scanner.go:51: s.device.StopScan undefined (type *bluetooth.Device has no field or method StopScan)
src/veyron/services/proximity/lib/bluetooth_scanner.go:52: s.device.Close undefined (type *bluetooth.Device has no field or method Close)
src/veyron/services/proximity/lib/bluetooth_scanner.go:60: s.device.StopScan undefined (type *bluetooth.Device has no field or method StopScan)
src/veyron/services/proximity/lib/bluetooth_scanner.go:61: s.device.Close undefined (type *bluetooth.Device has no field or method Close)

Since https://veyron-review.googlesource.com/#/c/3380/

Change-Id: I991de8fe2eb198ac794f0e37708e0bd792ed051b
3 files changed
tree: 6a2ffba44037754f98c97c0b38f709ca00eb1886
  1. examples/
  2. lib/
  3. runtimes/
  4. security/
  5. services/
  6. tools/