[wpimath] Explicitly export wpimath symbols

Co-authored-by: Tyler Veness <calcmogul@gmail.com>

wpimath/src/main/native/include/frc/kinematics/DifferentialDriveKinematics.h

@@ -4,6 +4,8 @@
 
 #pragma once
 
+#include <wpi/SymbolExports.h>
+
 #include "frc/kinematics/ChassisSpeeds.h"
 #include "frc/kinematics/DifferentialDriveWheelSpeeds.h"
 #include "units/angle.h"
@@ -19,7 +21,7 @@ namespace frc {
  * velocity components whereas forward kinematics converts left and right
  * component velocities into a linear and angular chassis speed.
  */
-class DifferentialDriveKinematics {
+class WPILIB_DLLEXPORT DifferentialDriveKinematics {
  public:
   /**
    * Constructs a differential drive kinematics object.