Update 2020 wpilib_interface.

Also remove an unused output field.

Change-Id: I9721fe923104b48984ab5895e28ef111c810d611
diff --git a/frc971/wpilib/ahal/AnalogTriggerOutput.cc b/frc971/wpilib/ahal/AnalogTriggerOutput.cc
index db55efa..1bbef1b 100644
--- a/frc971/wpilib/ahal/AnalogTriggerOutput.cc
+++ b/frc971/wpilib/ahal/AnalogTriggerOutput.cc
@@ -41,3 +41,5 @@
   HAL_Report(HALUsageReporting::kResourceType_AnalogTriggerOutput,
              trigger.GetIndex() + 1, static_cast<uint8_t>(outputType) + 1);
 }
+
+AnalogTriggerOutput::~AnalogTriggerOutput() {}