Use a bool for ForceDefaults instead of an int

The actual function takes a bool.

While we are doing this, add a couple missing ForceDefaults.

Change-Id: I7fd41c048dae340ca4f339230ceb033349db0faf
diff --git a/frc971/control_loops/drivetrain/improved_down_estimator_test.cc b/frc971/control_loops/drivetrain/improved_down_estimator_test.cc
index 26b27e9..a6d02f6 100644
--- a/frc971/control_loops/drivetrain/improved_down_estimator_test.cc
+++ b/frc971/control_loops/drivetrain/improved_down_estimator_test.cc
@@ -136,7 +136,7 @@
                                     Eigen::AngleAxis<double>(kPitch, uy) *
                                     Eigen::AngleAxis<double>(kRoll, ux));
   flatbuffers::FlatBufferBuilder fbb;
-  fbb.ForceDefaults(1);
+  fbb.ForceDefaults(true);
   fbb.Finish(dtukf.PopulateStatus(&fbb));
 
   aos::FlatbufferDetachedBuffer<drivetrain::DownEstimatorState> state(
diff --git a/frc971/control_loops/drivetrain/line_follow_drivetrain_test.cc b/frc971/control_loops/drivetrain/line_follow_drivetrain_test.cc
index 180af4b..c6bedf6 100644
--- a/frc971/control_loops/drivetrain/line_follow_drivetrain_test.cc
+++ b/frc971/control_loops/drivetrain/line_follow_drivetrain_test.cc
@@ -51,7 +51,7 @@
 
   void Iterate() {
     flatbuffers::FlatBufferBuilder fbb;
-    fbb.ForceDefaults(1);
+    fbb.ForceDefaults(true);
     Goal::Builder goal_builder(fbb);
     goal_builder.add_throttle(driver_model_(state_));
     goal_builder.add_controller_type(freeze_target_
@@ -105,7 +105,7 @@
 
   double GoalTheta(double x, double y, double v, double throttle) {
     flatbuffers::FlatBufferBuilder fbb;
-    fbb.ForceDefaults(1);
+    fbb.ForceDefaults(true);
     Goal::Builder goal_builder(fbb);
     goal_builder.add_throttle(throttle);
     fbb.Finish(goal_builder.Finish());
diff --git a/frc971/zeroing/imu_zeroer_test.cc b/frc971/zeroing/imu_zeroer_test.cc
index 9ec52da..8eef149 100644
--- a/frc971/zeroing/imu_zeroer_test.cc
+++ b/frc971/zeroing/imu_zeroer_test.cc
@@ -7,7 +7,7 @@
 aos::FlatbufferDetachedBuffer<IMUValues> MakeMeasurement(
     const Eigen::Vector3d &gyro, const Eigen::Vector3d &accel) {
   flatbuffers::FlatBufferBuilder fbb;
-  fbb.ForceDefaults(1);
+  fbb.ForceDefaults(true);
   IMUValuesBuilder builder(fbb);
   builder.add_gyro_x(gyro.x());
   builder.add_gyro_y(gyro.y());