backend/tests: Add blackbox tests from Kotlin JVM

Added tests from testData/codegen/box directory. There are blackbox tests
in other directories and they are to be added.

backend.native/tests/external/codegen/blackbox/instructions/swap/swapRefToSharedVarInt.kt

@@ -0,0 +1,11 @@
+fun box(): String {
+    var a: Int
+    a = 12
+    fun f() {
+        foo(a)
+    }
+
+    return "OK"
+}
+
+fun foo(l: Int) {}

backend.native/tests/external/codegen/blackbox/instructions/swap/swapRefToSharedVarLong.kt

@@ -0,0 +1,13 @@
+//KT-3042 Attempt to split long or double on the stack excepion
+
+fun box(): String {
+    var a: Long
+    a = 12.toLong()
+    fun f() {
+        foo(a)
+    }
+
+    return "OK"
+}
+
+fun foo(l: Long) {}