Made vararg parameters have Array<out T> type

instead of simply Array<T>
  #KT-1638 Fixed
  #KT-2163 Fixed
  #KT-3213 Fixed
  #KT-4172 Fixed
  #KT-5534 Fixed

compiler/testData/diagnostics/tests/inference/regressions/kt2200.kt

@@ -11,4 +11,4 @@ fun main(args: Array<String>) {
 }
 
 //from library
-fun <T> array(vararg t : T) : Array<T> = t
+fun <T> array(vararg t : T) : Array<T> = t as Array<T>

compiler/testData/diagnostics/tests/inference/regressions/kt2294.kt

@@ -13,4 +13,4 @@ public fun test()
 
 //--------------------
 
-fun <T> array(vararg t : T) : Array<T> = t
+fun <T> array(vararg t : T) : Array<T> = t as Array<T>