Implement explicit and implicit object pinning for interop

This allows passing Kotlin primitive arrays directly to native

backend.native/tests/interop/basics/3.kt

@@ -1,27 +1,19 @@
 import kotlinx.cinterop.*
 
 fun main(args: Array<String>) {
-    memScoped {
-        val count = 5
+    val values = intArrayOf(14, 12, 9, 13, 8)
+    val count = values.size
 
-        val values = allocArray<IntVar>(count)
-        values[0] = 14
-        values[1] = 12
-        values[2] = 9
-        values[3] = 13
-        values[4] = 8
+    cstdlib.qsort(values.refTo(0), count.toLong(), IntVar.size, staticCFunction { a, b ->
+        val aValue = a!!.reinterpret<IntVar>()[0]
+        val bValue = b!!.reinterpret<IntVar>()[0]
 
-        cstdlib.qsort(values, count.toLong(), IntVar.size, staticCFunction { a, b ->
-            val aValue = a!!.reinterpret<IntVar>()[0]
-            val bValue = b!!.reinterpret<IntVar>()[0]
+        (aValue - bValue)
+    })
 
-            (aValue - bValue)
-        })
-
-        for (i in 0 .. count - 1) {
-            print(values[i])
-            print(" ")
-        }
-        println()
+    for (i in 0..count - 1) {
+        print(values[i])
+        print(" ")
     }
+    println()
 }