Kotlin: Remove unused PopulationSpecFile

Author: igfoo

java/kotlin-extractor/src/main/java/com/semmle/extractor/java/OdasaOutput.java

@@ -39,7 +39,6 @@
 import com.semmle.util.exception.CatastrophicError;
 import com.semmle.util.exception.NestedError;
 import com.semmle.util.exception.ResourceError;
-import com.semmle.util.extraction.PopulationSpecFile;
 import com.semmle.util.extraction.SpecFileEntry;
 import com.semmle.util.files.FileUtil;
 import com.semmle.util.io.WholeIO;