KT-15871 Unnecessary boxing for equality operator on inlined primitive values

Allow kotlin.jvm.internal.Intrinsics#areEqual for boxed values.
Rewrite to primitive equality.

NB we can't do that for Float and Double, because java.lang.Float#equals
and java.lang.Double#equals behave differently from primitive equality comparisons.

compiler/testData/codegen/box/boxingOptimization/kt15871.kt

@@ -0,0 +1,5 @@
+fun box() =
+        if (getAndCheck({ 42 }, { 42 })) "OK" else "fail"
+
+inline fun <T> getAndCheck(getFirst: () -> T, getSecond: () -> T) =
+        getFirst() == getSecond()