Changed tracer to use an instance to hold state instead of statics.

Change-Id: I2fdcf5de7fbc745273b1a33cb409d13e72d24ab4
diff --git a/src/dalvik_system_VMDebug.cc b/src/dalvik_system_VMDebug.cc
index c4c43f1..c388e62 100644
--- a/src/dalvik_system_VMDebug.cc
+++ b/src/dalvik_system_VMDebug.cc
@@ -92,7 +92,7 @@
 }
 
 jboolean VMDebug_isMethodTracingActive(JNIEnv*, jclass) {
-  return Trace::IsMethodTracingActive();
+  return Runtime::Current()->IsMethodTracingActive();
 }
 
 void VMDebug_stopMethodTracing(JNIEnv*, jclass) {