IR: IrSimpleFunction.correspondingProperty: IrProperty?

Non-null for a property accessor, points to a corresponding property.

compiler/testData/ir/irText/classes/dataClassesGeneric.txt

@@ -16,6 +16,7 @@ FILE fqName:<root> fileName:/dataClassesGeneric.kt
         EXPRESSION_BODY
           GET_VAR 'value-parameter x: T' type=T origin=INITIALIZE_PROPERTY_FROM_PARAMETER
       FUN DEFAULT_PROPERTY_ACCESSOR name:<get-x> visibility:public modality:FINAL <> ($this:Test1<T>) returnType:T flags:
+        correspondingProperty: PROPERTY name:x type:T visibility:public modality:FINAL flags:val
         $this: VALUE_PARAMETER name:<this> type:Test1<T> flags:
         BLOCK_BODY
           RETURN type=kotlin.Nothing from='<get-x>(): T'