PLock remove unused imports

Author: cosminbasca

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/thread/PLock.java

@@ -44,7 +44,6 @@
 import java.util.concurrent.TimeUnit;
 
 import com.oracle.graal.python.builtins.objects.type.LazyPythonClass;
-import com.oracle.graal.python.builtins.objects.type.PythonClass;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 
 public final class PLock extends AbstractPythonLock {