KT-4152 Wrong postfix increment/decrement calculation

#KT-4152 Fixed

compiler/testData/codegen/box/intrinsics/prefixIncDec.kt

@@ -0,0 +1,29 @@
+public var inc: Int = 0;
+
+public var propInc: Int = 0
+    get() {++inc; return $propInc}
+    set(a: Int) {
+        ++inc
+        $propInc = a
+    }
+
+public var dec: Int = 0;
+
+public var propDec: Int = 0;
+    get() { --dec; return $propDec}
+    set(a: Int) {
+        --dec
+        $propDec = a
+    }
+
+fun box(): String {
+    ++propInc
+    if (inc != 3) return "fail in prefix increment: ${inc} != 3"
+    if (propInc != 1) return "fail in prefix increment: ${propInc} != 1"
+
+    --propDec
+    if (dec != -3) return "fail in prefix decrement: ${dec} != -3"
+    if (propDec != -1) return "fail in prefix decrement: ${propDec} != -1"
+
+    return "OK"
+}