Generate correct varargs flag for @JvmOverloads-generated methods

#KT-14186 Fixed

compiler/testData/codegen/box/jvmOverloads/varargs.kt

@@ -0,0 +1,16 @@
+// IGNORE_BACKEND: JS
+
+// WITH_RUNTIME
+
+class C {
+    @JvmOverloads
+    fun foo(bar: Int = 0, vararg status: String) {
+
+    }
+}
+
+fun box(): String {
+    val c = C()
+    val m = c.javaClass.getMethod("foo", Array<String>::class.java)
+    return if (m.isVarArgs) "OK" else "fail"
+}