Make Java AnalogGyro.getAngle() thread-safe.

In the Java implementation, "result" is an instance variable (to avoid
needing to perform a memory allocation on each call to getAngle).  However,
this means that calls to getAngle() from multiple threads can step on each
other.  Synchronize the method to avoid this issue.

Reported by: Jackson Gray (http://www.chiefdelphi.com/forums/showthread.php?threadid=145124)

Note this does not synchronize accesses between configuration methods such
as calibrate() and accessor methods such as getAngle().

Change-Id: I9ecc962d4fba66f6134fd801cfd607f155b41fe5

wpilibj/src/athena/java/edu/wpi/first/wpilibj/AnalogGyro.java

@@ -165,7 +165,7 @@ public class AnalogGyro extends GyroBase implements Gyro, PIDSource, LiveWindowS
   /**
    * {@inheritDoc}
    */
-  public double getAngle() {
+  public synchronized double getAngle() {
     if (m_analog == null) {
       return 0.0;
     } else {