Allow secondary constructors without body

#KT-6967 Fixed

compiler/testData/codegen/box/secondaryConstructors/accessToCompanion.kt

@@ -11,7 +11,7 @@ class A(val result: Int) {
     object C {
     }
 
-    constructor() : this(foo() + prop + B.bar() + B.prop + C) {}
+    constructor() : this(foo() + prop + B.bar() + B.prop + C)
 }
 
 fun box(): String {

compiler/testData/codegen/box/secondaryConstructors/clashingDefaultConstructors.kt

@@ -1,13 +1,13 @@
 open class A(val x: String = "abc", val y: String = "efg") {
-    constructor(x: String, y: String, z: Int): this(x, y + "#" + z.toString()) {}
+    constructor(x: String, y: String, z: Int): this(x, y + "#" + z.toString())
     
     override fun toString() = "$x#$y"
 }
 
 class B : A {
-    constructor(x: String, y: String, z: Int): super(x, y + z.toString()) {}
-    constructor(x: String = "xyz", y: String = "123") : super(x, y)  {}
-    constructor(x: Double): super(x.toString()) {}
+    constructor(x: String, y: String, z: Int): super(x, y + z.toString())
+    constructor(x: String = "xyz", y: String = "123") : super(x, y)
+    constructor(x: Double): super(x.toString())
 }
 
 fun box(): String {

compiler/testData/codegen/box/secondaryConstructors/delegationWithPrimary.kt

@@ -9,7 +9,7 @@ class B : A {
 val global = B()
 
 class C(x: Int) : A by global {
-    constructor(): this(1) {}
+    constructor(): this(1)
 }
 
 fun box(): String {

compiler/testData/codegen/box/secondaryConstructors/generics.kt

@@ -1,11 +1,11 @@
 open class B<T>(val x: T, val y: T) {
-    constructor(x: T): this(x, x) {}
+    constructor(x: T): this(x, x)
     override fun toString() = "$x#$y"
 }
 
 class A : B<String> {
-    constructor(): super("default") {}
-    constructor(x: String): super(x, "default") {}
+    constructor(): super("default")
+    constructor(x: String): super(x, "default")
 }
 
 fun box(): String {