Cleanup.

Author: lahodaj

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/ExhaustivenessComputer.java

@@ -40,7 +40,6 @@
 import com.sun.tools.javac.code.Kinds.Kind;
 import com.sun.tools.javac.code.Type.TypeVar;
 import java.util.Arrays;
-import java.util.IdentityHashMap;
 import java.util.Iterator;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;