Missing Windows symbols

[virtuald]

Building RobotPy alpha yields the following errors on Windows:

 LEDPattern.obj : error LNK2001: unresolved external symbol "public: static class frc::LEDPattern frc::LEDPattern::kOff" (?kOff@LEDPattern@frc@@2V12@A)
SensorUtil.obj : error LNK2001: unresolved external symbol "public: static int const frc::SensorUtil::kAnalogOutputs" (?kAnalogOutputs@SensorUtil@frc@@2HB)
SensorUtil.obj : error LNK2001: unresolved external symbol "public: static int const frc::SensorUtil::kPwmChannels" (?kPwmChannels@SensorUtil@frc@@2HB)
SensorUtil.obj : error LNK2001: unresolved external symbol "public: static int const frc::SensorUtil::kRelayChannels" (?kRelayChannels@SensorUtil@frc@@2HB)
SensorUtil.obj : error LNK2001: unresolved external symbol "public: static int const frc::SensorUtil::kAnalogInputs" (?kAnalogInputs@SensorUtil@frc@@2HB)
SensorUtil.obj : error LNK2001: unresolved external symbol "public: static int const frc::SensorUtil::kDigitalChannels" (?kDigitalChannels@SensorUtil@frc@@2HB)

Per Peter, because #6979 et al, needs to either be declspec(dllimport) or converted to getter functions. Doesn't matter to me either way. dllimport is less breaking for the SensorUtil items? Though, not sure who uses them.

[ThadHouse]

dllimport doesn't work, because it breaks the static linking scenario. They must be converted to getter functions.