Added missing specificity comparator to FIR

This is required to correctly resolve overloading in cases when we
need to find most specific alternative in Java between int and Integer.

compiler/testData/diagnostics/tests/j+k/primitiveOverrides/specializedMap.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // FILE: AbstractSpecializedMap.java
 public abstract class AbstractSpecializedMap implements java.util.Map<Integer, Double> {
     public abstract double put(int x, double y);