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)
+}