JVM_IR KT-45187 use Arrays.copyOf to copy an array in spread operator

Creating a new array (and copying data into it with System.arraycopy)
doesn't work in generic case, because the actual array class depends on
call site.

compiler/testData/codegen/box/vararg/kt45187.kt

@@ -0,0 +1,13 @@
+// TARGET_BACKEND: JVM
+
+fun box(): String =
+    object : A<Void, Void>() {
+        override fun f(vararg params: Void): Void? = null
+    }.execute()
+
+abstract class A<P, R> {
+    protected abstract fun f(vararg params: P): R?
+
+    fun execute(vararg params: P): String =
+        if (f(*params) == null) "OK" else "Fail"
+}