K2 opt-in: restore marker annotation check for constructors

compiler/testData/diagnostics/testsWithStdLib/experimental/constructorCheck.kt

@@ -0,0 +1,23 @@
+// FIR_IDENTICAL
+@RequiresOptIn
+annotation class Marker
+
+@Marker
+class Some(val x: Int)
+
+class Other(val x: Int) {
+    @OptIn(Marker::class)
+    constructor(some: Some): this(some.x)
+
+    @Marker
+    constructor(): this(42)
+
+    @OptIn(Marker::class)
+    constructor(y: Long, some: Some? = null): this(some?.x ?: y.toInt())
+}
+
+fun test() {
+    val o1 = <!OPT_IN_USAGE_ERROR!>Other<!>()
+    val o2 = Other(<!OPT_IN_USAGE_ERROR!>Some<!>(0))
+    val o3 = Other(444L)
+}

compiler/testData/diagnostics/testsWithStdLib/experimental/constructorCheck.txt

@@ -0,0 +1,29 @@
+package
+
+public fun test(): kotlin.Unit
+
+@kotlin.RequiresOptIn public final annotation class Marker : kotlin.Annotation {
+    public constructor Marker()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Other {
+    @Marker public constructor Other()
+    @kotlin.OptIn(markerClass = {Marker::class}) public constructor Other(/*0*/ some: Some)
+    public constructor Other(/*0*/ x: kotlin.Int)
+    @kotlin.OptIn(markerClass = {Marker::class}) public constructor Other(/*0*/ y: kotlin.Long, /*1*/ some: Some? = ...)
+    public final val x: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+@Marker public final class Some {
+    public constructor Some(/*0*/ x: kotlin.Int)
+    public final val x: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}