Removed unused imports

Author: Zhengyu Gu

substratevm/src/com.oracle.svm.hosted.jdk11/src/com/oracle/svm/hosted/jdk11/jfr/JfrEventSubstitution.java

@@ -38,7 +38,6 @@
 import com.oracle.graal.pointsto.infrastructure.OriginalClassProvider;
 import com.oracle.graal.pointsto.infrastructure.SubstitutionProcessor;
 import com.oracle.svm.core.jdk11.jfr.JfrJavaEvents;
-import com.oracle.svm.core.jdk11.jfr.SubstrateJVM;
 import com.oracle.svm.core.util.VMError;
 import com.oracle.svm.hosted.c.GraalAccess;
 

substratevm/src/com.oracle.svm.hosted.jdk11/src/com/oracle/svm/hosted/jdk11/jfr/JfrFeature.java

@@ -51,7 +51,6 @@
 import com.oracle.svm.hosted.FeatureImpl;
 import com.oracle.svm.core.jdk11.jfr.JfrEnabled;
 import com.oracle.svm.core.jdk11.jfr.JfrFrameTypeSerializer;
-import com.oracle.svm.core.jdk11.jfr.JfrJavaEvents;
 import com.oracle.svm.core.jdk11.jfr.JfrManager;
 import com.oracle.svm.core.jdk11.jfr.JfrSerializerSupport;
 import com.oracle.svm.core.jdk11.jfr.SubstrateJVM;