Migration to expect/actual: fix multiplatform integration tests

compiler/testData/multiplatform/genericDeclarations/common.kt

@@ -1,13 +1,13 @@
-header fun <T> f1(): T
+expect fun <T> f1(): T
 
-header fun <T> f2(t: T)
+expect fun <T> f2(t: T)
 
-header fun <K : Enum<K>, V : MutableList<out K>> f3(v: Map<V, Enum<in K>>, w: Comparable<*>)
+expect fun <K : Enum<K>, V : MutableList<out K>> f3(v: Map<V, Enum<in K>>, w: Comparable<*>)
 
-header fun <T: Comparable<T>> Array<out T>.sort(): Unit
+expect fun <T: Comparable<T>> Array<out T>.sort(): Unit
 
-header class C1<A>
-header class C2<B : C2<B>>
-header class C3<D, E : MutableList<in D>>
+expect class C1<A>
+expect class C2<B : C2<B>>
+expect class C3<D, E : MutableList<in D>>
 
-header abstract class AbstractList<F> : MutableList<F>
+expect abstract class AbstractList<F> : MutableList<F>

compiler/testData/multiplatform/genericDeclarations/jvm.kt

@@ -1,15 +1,15 @@
-impl fun <T> f1(): T = throw AssertionError()
+actual fun <T> f1(): T = throw AssertionError()
 
-impl fun <T> f2(t: T) {}
+actual fun <T> f2(t: T) {}
 
-impl fun <K : Enum<K>, V : MutableList<out K>> f3(v: Map<V, Enum<in K>>, w: Comparable<*>) {}
+actual fun <K : Enum<K>, V : MutableList<out K>> f3(v: Map<V, Enum<in K>>, w: Comparable<*>) {}
 
-impl fun <T: Comparable<T>> Array<out T>.sort(): Unit {
+actual fun <T: Comparable<T>> Array<out T>.sort(): Unit {
     java.util.Arrays.sort(this)
 }
 
-impl class C1<A>
-impl class C2<B : C2<B>>
-impl class C3<D, E : MutableList<in D>>
+actual class C1<A>
+actual class C2<B : C2<B>>
+actual class C3<D, E : MutableList<in D>>
 
-impl abstract class AbstractList<F> : MutableList<F>, java.io.Serializable
+actual abstract class AbstractList<F> : MutableList<F>, java.io.Serializable