Allow secondary constructors without body

#KT-6967 Fixed

compiler/testData/diagnostics/tests/secondaryConstructors/generics.kt

@@ -1,21 +1,21 @@
 // !DIAGNOSTICS: -UNUSED_PARAMETER -UNREACHABLE_CODE
 open class B<T>(x: T, y: T) {
-    constructor(x: T): this(x, x) {}
-    constructor(): this(null!!, null!!) {}
+    constructor(x: T): this(x, x)
+    constructor(): this(null!!, null!!)
 }
 
 class A0 : B<String?> {
-    constructor() {}
-    constructor(x: String): super(x) {}
-    constructor(x: String, y: String): super(x, y) {}
+    constructor()
+    constructor(x: String): super(x)
+    constructor(x: String, y: String): super(x, y)
 }
 
 class A1<R> : B<R> {
-    constructor() {}
-    constructor(x: R): super(x) {}
-    constructor(x: R, y: R): super(x, y) {}
+    constructor()
+    constructor(x: R): super(x)
+    constructor(x: R, y: R): super(x, y)
 }
 
 class A2<R> {
-    constructor(t: R, i: Int) : <!CYCLIC_CONSTRUCTOR_DELEGATION_CALL!>this<!>(<!TYPE_MISMATCH!>i<!>, 1) {}
+    constructor(t: R, i: Int) : <!CYCLIC_CONSTRUCTOR_DELEGATION_CALL!>this<!>(<!TYPE_MISMATCH!>i<!>, 1)
 }